I'd suggest reading the sticky thread. There is some great information in that FAQ which I used to help buy my first MR2 this past November. Its a good starting point, and the rest you can probably learn from the forum.

 

Just a few pointers for things to look at:

1. What kind of shape is the body in, especially the rumble strips?

2. How good are the syncros? (known weak point)

3. Are there any visible oil leaks?

4. Does the car fart blue smoke on start up? (valve seals are infamous for leaking when cold)

5. Is there any odd behavior when turning that might indicate problems with the strut mounts?(infamous)

6. Are the strut replacements OEM or something else? Either way, make sure you test the drivability, mixxed suspension components = bad juju.

7. How does the car look underneath for rust?

8. Do both windows and door lock switches work? (Wiring harness in drivers door also infamous)

9. Does the brake master cylinder still feel strong under heavy braking? (Had to replace mine a month after I got the car)

10. When you take the car to get checked out make sure that they test the wheels for play which might indicate issues with ball joints or wheel bearings.

11. If it's a T-top what kind of shape are the seals in? Any leaking?