my advice for buying a used 09 in the future isnt going to differ from buying any other used subaru. make sure you research the car youre getting. look for one that is STOCK with low milage. one owner is preferred. checked the carfax, blah blah.
we have a great forum here for buying used subies:
How to Buy a Used WRX or STI
if worse comes to worse, when the time comes just post back here with a link to the for sale ad & we will give you our input