There's a few questions here, what spec are you looking for?
UK or Jspec?
TT or N/A?
5spd, 6spd or auto?
It's definitely worth looking at the guides available on here before deciding as I found them to be a great help.
Also, if you get any photos of a car you like the look of, post them up on here so other members can give their opinion.
As drift_bear already mentioned, the PDF "What to look out for" is very detailed and is useful if you're not familiar with the Supra.
Good luck with your search, I had dreamt about owning one for years and finally managed to get one, I was not disappointed!!