Definitely spend time looking and be prepared to travel, there are a few lemons out there both private and dealer ones.
I've wanted a Supra since I could walk and being a petrolhead went to for twin turbo which I picked up last May. I buy and sell cars on the side so knew what to look out for with the help of a few guides on here and got a good car for a really good price.
Even so in the last 15 months I have replaced many ageing parts, and a few mods (exhaust, fuel pump, fcd and boost controller is on order which should be around the 380-400bhp) which is plentiful! Then if they blow I'll just go single turbo aiming for 500-550bhp
Paintwork is another area to keep your eyes peeled on, no matter how shiny it is on top the underside/arches will need attention unless it has been treated.
If you just want the looks and aura of driving a Supra then get a non-turbo, but if you like your turbos and boooooost then get a TT or single turbo (400bhp+).