First of all, I don’t have extensive experience negotiating boat purchases.  Personally and professionally, real estate transactions are more my forte but I think they share some commonality.
 
My fist bit of advice – Don’t get too excited or impatient. If the deal does not seem right, walk away.  Be prepared to wait for another, and likely, better boat to come along.  Put the costs of the survey down to valuable experience.  (The old adage is true – He/she who cares the least wins.)
 
There are a few questions I’ll try to work around - Was the boat offered for sale “as-is” and priced accordingly?  Was it advertised as “cruising ready”?  You did not say if you are working with/through a broker or if you’ve signed a “standard” P&S agreement.
 
I'd say “industry protocol” concerning negotiations, offer/acceptance, terms, etc. is specified in the purchase and sale agreement, assuming you have one.  Typical purchase/sale agreements contain a clause that says your offer is subject to your obtaining satisfactory survey and sea trial – that’s to your satisfaction.  You probably already know this.  Typically, there’s also a condition that says you have so many days to obtain a survey and sea trail or you are deemed to accept the boat as-is.  Assuming time hasn’t run out, my advice is to reject the boat.
 
Why?  Well it seems to me, based on what 25 yr. old 36’s are selling for; a $7500 repair tab is, in my opinion, too high a percentage of the overall purchase price.  I’m assuming an asking price is the $50-60k neighborhood.  Depending on if the terms of your agreement/offer allow it, I’d reject the boat (withdraw my offer) and present a new offer for more/less the same amount less all expected repairs needed to get the boat in a safe and operable condition – not as good as new, but safe and operable.  That means it’s mechanically functional and structurally sound.  That does not mean things that normally wear out are made good as new.  To elaborate, if your surveyor says electronics, fire extinguishers, bottom paint, dinghy, etc. aren’t functioning or should be replaced, I probably wouldn’t adjust my offer significantly because, as you seem to know, most owners expect to pay some of their own “move-in” expenses.  If you were told there’s no compression in one of the engine cylinders, or the rudder is waterlogged, yes you should factor those repairs into your revised offer.
 
My 2c are based on the information provided and my own personal experiences and prejudices.  Others may disagree me, perhaps vociferously.  If you tell us more about the issues the surveyor turned up, whether or not you have a “standard” agreement, the overall condition of the boat, and (generally) where you are located, then perhaps me and others may be able to provide better advice.
 

I purchased my boat last year, and my advice is to remember that your are dealing with a used car salesmen.  As soon as you hand over the check, you inherit all the problems, don't expect help.  At a minimum offer 10% less than the asking price, plus all the known "major" issues issues.  Tip top to you, may not be tip top to others. 

There are so many variables that can go wrong, expect to put in an additional 5% to 10% of the purchase price to to cover the unknowns.  I offered 10% less and got it, however I had to put in an additional 10% in unknown repairs. However, you have made the right choice.. the Catalina 36 is worth it! 
Good Luck... 

And another thing…(in a nice way)
 
You said “I don’t want to offend the seller”. I wouldn't be concerned unless they're a personal friend, relative, or acquaintance.  Are you worried he’ll take his boat and go home and you’ll lose the boat you’ve got your heart set on?  If so, don’t worry. These emotions are normal for a first –time buyer.  Just remember: you are handing over a lot of your hard earned money to a stranger and in all likelihood, he’s only looking to unload his boat on the first person he can.  Guess what - you just happened to come along first.
 
Don’t be afraid of insulting the seller. If they are honest, they’ll agree to an adjustment without any qualms.  If they throw a big fit, act insulted and threaten to break off negotiations, I’d suspect they are knowingly playing on the emotions of a first-time buyer.  Remember, he probably needs to sell a whole lot more than you need to buy.  That puts you in a strong position.  Again, just my 2c worth.
 

I am guessing the broker has come back and said he has a second offer waiting.  That is sort of standard used car tactics.  The blue book for boats is pretty exaggerated in my opinion.  The pricing is so thin on used boats that the rating agencies are not using reality.  In addition you have to factor in the prices are really driven off of well equipped boats on the coast.  If you are not on the coast and the boat is not decked out with expensive equipment then discount the prices substantially.

$7500 is a steep repair bill.  I would adjust your offer down if the boat was not already marked down to reflect the needed repairs.  Now that the survey is done the broker and owner are going to be in a position of knowing the issues exist and either accepting the boat needs repair or looking for a sucker. There are not that many marine surveyors in any given town and all are going to catch major issues - as much as brokers may tell you that it is a surveyor's opinion they are more fact driven especially when it comes to repairs.

In addition you can't just ignore the repairs.  You will get a letter from your insurance company asking for proof that any repairs required by the survey are completed (unless they are cosmetic).

I have an '87 C36 and have replaced light fixtures, cabin floor, windows, sails and lifelines (not to mention regular replacement of lines, bottom paint, and batteries).  I could still spend more on cushions, drapes refrigerator, etc.)  Fortunately being in fresh water I don't have the corrosion issues with my rigging.  I would look for others to chime in but consider these intangibles when pricing a 26 year old boat:
    in salt or fresh water?  - matters to the rigging and other corrosion sensitive systems
    year round in the water or hauled out for winter?  - northern boats often get only 4 months of use
    engine hours - they are not like cars, I am guessing around 5k hours you are looking at overhaul/replacement
    deck integrity -  these decks have coring and if it fails it is and expensive repair that must be done
    sail condition - this is a significant cost to replace the sails, how old are they?

Your timing is good as boat sales are slow during winter.  Used sailboats are a buyers market.

That said the 36 is a very good boat to buy (IMHO).  It is comfortable and easy to sail. 

Five years ago I purchase a 92 and like you I was a novice sailor/owner. Some one told me to spend 70% of my budget on the boat and save 30% for known and unknown stuff. This may be less true of a much newer boat but has turned out to be exactly correct for me.  Even if you get relief from a seller with the "gotta haves" you will have known and unknown "wanna haves" as you settle into your boat. 
All the above advice is well thought out and sound and you will find a Catalina 36 a joy to own and sail.

There was only one boat on Yachtworld with your criteria. If the pictures are current, it looks like the boat is (or was) in my marina (VIM), maybe H or I dock. Sorry, I cant say I know anything about the boat or owner.  Price doesn't seems out of line.  If the two of you buy it and have questions, drop by G32 and say hello. Also, the people at Ventura Harbor Boatyard have always been fair and square with me.  I plan on using them again when needed. Good luck.

Sounds like the boat next me in Ventura. H dock? It has been on the market for some time. I haven't seen it leave the slip in a long while. Does look like a good boat. I think the owner told me his kids are grown and he just doesn't use the boat.
The one thing I found when buying Island girl was having a nice relationship with the seller was a good thing. My seller left a ton of extras on the boat that he could have taken and sold at a swap meet. My seller was straight fwd and honest before the any inspections. I paid the price we had already agreed to. He was asking 77500 and we agreed to 72500. I wanted this boat, It had been loved.

If you are in Southern California (as am I) and the boat has significant repairs needed, I would discount my offer.  There are countless C36 MKI's always available up and down the coast, and many are in very good condition, so you should get the discount or walk away.  Wait for the right boat.