definately make sure that the 90k maitenance has been done... if you can get proof it was done somehow, that would be best.

i would suggest you do a compression/leakdown test if you can manage it somehow. I would suggest you have a loyal mechanic to give it a once over after you purchase it as well...

also if it is a GSR, it may have a little rattle between 3k and 4k, it's just the heat shield and is easily solved.

the steering wheel may wobble a little bit during braking.... it's the brakes... unless they have been changed out from stock, they will generally cause a slight shimmy in the wheel during braking.

also look out for any lights (check engine, ABS, mait reqd) and be sure to inqure when they came on and what they did about it. besides that i can't think of anything just be careful and look at every bit you can