I know this is an old post put I couldn't help but drop a line...
12,000 dollars for an 83 supra is f---ing ludicrous and absurd. If someone actually bought it for anywhere near that price those dealers are gonna be all straight faced and sh-- until they go to the back room and they'll be jumping up and down like those old tv commercials (oh, what a feeling). Dude, they'd send out for champagne and be telling their grandkids about it for years.
I know of this guy who answered an ad for a 1953 mercedes sports car around 1985 and went to this house where the car had been in the garage for 30 years after the owner who had originally bought it died. His wife just kept it there, and to top it off, she even covered it and used leather preserver on the upolstery every year. The car was like new, and not only was it a rare and sought after model, this one was unique in that it had a fiberglass body (non-magnetic) and was only one of seven or so that was used as a race car and then 'converted' back to a regular stock car to be sold. He offered the lady 20,000 dollars for it and before he came back the next day to finalize the transaction he researched the vin and found out that this car was worth about 175,000. he already had a cash offer for 120k by the time he towed it to his house.
I don't think that the supra would be anywhere near as valuable as the 54 gullwing or a rolls or, um. those "nightmare before christmas" toys but to each his own.
By the way I have a 93 camry 4cyl. Although it's only worth about 2-3k, I'd be happy and more than willing to sell it to your for 50,000 dollars. It's only been in two accidents though repaired. It has 150k miles or so, and paint chips and a cracked windshield. I did clean the carpetting on it though.