Lots more info below.........I did actually look in to getting one.....

Aftermarket Parts
http://www.motorsportworld.co.uk/
http://www.fensport.co.uk/products.htm
http://www.toyheadauto.com/Performan..._Bushings.html

Technical info
http://opc.mr2oc.com/
http://www.carmanuals.btinternet.co.uk/

Celica GT4 specialist breaker (based in cornwall but ship parts to you)
http://www.tcbperformanceparts.co.uk/welcome.htm
http://www.tcbparts.co.uk/

ST165 & ST185 common faults:
Failed electric aerial (new one is over £200)
Radiator cap failure
Intermittent starter motor (tcb £40.00)
Rusted sunroof
Rear defogger element failure (new rear glass is over £400)
engine oil leaks
gearbox oil leaks
Aircon compressor failure (look for flashing aircon light)
Clutch wear
Turbo inlet & outlet pipe splits
TVIS butterfly valve rattle (at over 4300rpm)
Check engine light code 54 (intercooler water level low) - not a big deal