hey, I don't know why everyone here is bashing the TA, it's a good car generally speaking, RWD, gobs of torque, abundant HP.
I prefer older TA's however, the newer ones are okay, and very tunable. But remember this:
USED TA's are usually beat to hell, because mostly young drivers are the previous owners, and they beat the hell out of their rides 80% of the time.
what are the miles like? if it's under 50K on the odo, it may be okay. less miles are better.
It's RWD, it's horrid in the winter, and the rear axle is straight across (no independant rear suspension)
It may be nice in good weather, on the 1/4 mile, but you will need a LOT of suspension mods to make it handle like a celica.
Lastly, if it's a V6, stay away from it! it's not worth the money. If it has the firehawk conversion, or another high-performance option from the factory, it is an especially desireable car.
Now, the advantages:
Engine swaps are a no-brainer on this one, lots of GM motors will work in this thing, as will some ford motors.
Mass produced, so many replacement part are available dirt cheap from salvage yards & such. Also, this car has a HUGE aftermarket. you will have no trouble finding mods for a TA.
Last bit of advice I have is to check it out thouroughly, make sure the miles aren't too hiogh, the brakes and engine are in good order, and the tranny doesn't slip or grind. if there is any little problem that nags you, don't buy it! while they are fun musclecars to build and wrench on, they are known for having issues. be prepared to have to fix something every once in a while.