It's always hard to tell, I would have to assume that even for one of these caution must be excercised when it's that sort of miles and who knows how it's been driven? Might consider posting such a question on a Supra forum, this one seems to not be too active.
What are the mileages on the ones you indicate you found through your dealer? I could try looking at this car on Friday if you're interested as I have a meeting in Chicago in the early evening and wouldn't mind driving it myself. Hard to tell much about condition with that *really poor* photo from the near-square on front. Does not tell you much. I can try to call them tomorrow, but you know the line they will say...
There is a V-8 SC400 auto near my house that is a '92 with a flawless interior, 80k miles, two owners, and a somewhat high asking price of $8995. So they are not too far off with $4500, likley. It would make, perhaps, a good project car. Let me know what you think.
-Randy