you have a 911 targa...and your looking at a used wrx....hoepfuly the 911 isnt new
Oh well back to your question. There are a few things to look for and they are:
Ask if the car had the clutch shudder fixed
Two warranties so far...make sure they were performed
And lastly...Look for signs of mods.
If you read a few threads alot of people are going back to stock...this leaves alot of raped wrx to be sold. If i was you if has an aftermarket BOV or any other stupid kind of mod, aire on the side of caution. The one 02 I looked at had a BOV, and FRESH STOCK 43,000 miles exhaust with FRESH bolts holding the turbo in. Also it had ECUTec stickers under the hood......gee i'm sure it wasnt raped Oh well....good luck