I would no doubt request to see the service history on the vehicle. Ask the owner for his login on my.subaru.com and that should give you access to view the warrenty work performed on the vehicle. Otherwise I ask him to have the dealer fax over the history. The reason I bring this up is b/c I would expect the earlier(if not all) '02s to have the clutch relplaced under warrenty for "cold clutch shudder" there is TSB on the issue. At 100k if you're still on the original clutch I would expect a replacement soon. On the flip side If this is an original clutch this would be a sign that the car wasn't abused.

I would inspect the vehicle for tell tale signs of removed modifications. I would pay close attention to hoses going to the turbo and boost controller. Inspect the exhaust bolts and the turbo heat sheild for evidence of prior modifications. Don't forget to check for collision damage. A slighly trained eye can easily spot repairs if you're looking for them. I would suggest running a carfax but don't rely on the information to be 100% accurate.

I would have the vehicle checked out by 3rd party mechanic that has experience with Subarus. I would consider Mastro but any mechanic with prior experience should do. Assuming everything checks out I would seriously consider the car for 12k. It's a deal!