FYI, if you dont have much money, I would be very careful about buying a Subaru with a Turbocharged 2.5 engine (EJ255). First of all they run on premium gas, secondly they require much more maintenance than most cars. The turbo's regularly go around 100k - with the possibility of taking the engine with it. The oil change intervals are 3000 miles, miss it at your turbos peril. The 05/06 models have a catted up pipe which also takes the turbo/engine with it if/when it melts. This information is pretty easy to find on the web.
Having said all that, I wouldn't trade my Legacy for ANYTHING. I love the damn thing, if you keep up with the maintenance and the person before you did, they are great cars.
The 2.2 subaru engine is known to be pretty bulletproof, and the 2.0 Turbo in the WRX is known to be pretty good also. I am extremely surprised that you cant find any under 15k. I bought my high mile 05 LGT for about 9k.
You can pick the bugeye wrx's up for pretty cheap, I have seen some wagons for under 7k. Good luck whatever you buy.