I paid $3800 for my 1986 GT ... not quite mint condition, but still in bloody good nick. Leather on the back seats is fine, both front seats need replacing though. No rust, and just a few clicks and squeals that you'd expect from a 20 year old car.
Pic:
http://toyspeed.blakjak.net/profiles/profile.php?id=108
[edit ... just realised you've posted a comment in there
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If the car hadn't been modified as it has, it would only be worth about $2000 to me. I would say the people selling the car you want are being quite unrealistic with it.
I would speak to them about it, take a very close look at the car, and point out any flaws you see in it straight away. Take it for a drive and do the same thing. Quite often they will point out a couple of small problems with the car themselves. Make a mental note of as many of these problems as you can, then go back to them and say something along the lines of "I like the car, but its almost 20 years old, has this, this and this wrong with it, and as you pointed out, also has that wrong with it. I will offer you $xx for it, but can't justify spending more than that."
Usually works a treat
BTW, I love my AE82, wouldn't trade it for the world