For 3K you should get a low milage immaculate 53 plate ST170, value has dropped massively on these, they are worth very little now due to the running costs, high tax, insurance, MPG in the low 20's and not great performance. There are allot of dreamers out there, mostly commercial garages.
A 90K 2002 ST170 could be picked up for £1500 easily.
Gearbox is a Getrag 6 Speed, absolutely bomb proof should give you no problems, the weak points are the Dual Mass Fly wheel, make sure this has been changed on a high milage car otherwise a new clutch and fly will set you back £600+, fuel pumps, coil packs, rotten sumps, lambda sensors, IMRC,and general abuse by boy racers, the standard wheels corrode badly too.
If there was on thing i would look for is hold out for an ST170 with Xenon headlights, they are worth the wait.
I used a Bluefin handset to read codes on mine