Not a WRX STI Subaru
In the alphabet soup subaru world there is a performer that can be had On The Cheap, but be cautious
To be perfectly honest, this car straddles the line between cheap and expensive. Produced between 2003 and 2009 the Subaru Legacy BL and BP came to the U.S. in GT trim starting in 2005. With a Turbocharged 2.5 Liter Horizontally Opposed (Boxer) 4 Cylinder with dual over head cams and AVCS on the intake cams.
This is the point where a word of warning comes into play, as well as potentially pushing this car out of the cheap territory and into the OMG How Much?! range.
The EJ255 engine in the U.S. Spec Legacy GTs may have won great acclaim, as it is the the same engine used in the U.S. Spec 2006 and up WRX, but there are several problems with these engines which can cost as much a buying another car to repair or replace.
Cheap, disposable turbochargers. While not astronomical in price, these turbos are fragile and Subaru knew it. In order to "protect" the turbo there are tiny oil filters installed in the banjo bolts which connect the oil feed lines to the turbo. You don't even have to miss an oil change for these filters to clog which will then starve the turbo of oil and in the best scenario you just replace the turbo and remove the line filters. In the bad scenario, the turbo compressor wheel grenades blowing chunks of shrapnel into the intercooler and in the biblically bad scenario this debris makes it's way into the engine.
Another potentially disastrous issue is the timing belt. While reportedly good for 120K miles of carefree driving, the timing belt tensioner and idler pulleys are not to be trusted beyond 100K miles. If any component in the timing belt system fails, valves will impact the pistons. Bad scenario is 4 or 8 bent valves, catastrophic scenario is 16 valves bent with piston or cylinder wall damage.
There is something about a Subaru fanatic, and I have been one, that makes them think that rebuilding or replacing an engine in these cars is worth $3000 or more. They're overly complicated, and while they produce an absurd amount of power for their displacement, raising the hood and removing the engine cover will make you think this thing is on life support. Just the block and heads with no hoses, accessories or manifolds weighs only about 250 pounds, but once it is in the car, it tips the scales over 400 pounds, and the intake manifold is plastic.
U.S. Spec Legacy GT Sedan
However... finding a well maintained Legacy GT, and investing in some preventative maintenance and minor upgrades will not cost a fortune, and it's quite possible to find one of these cars for around $6000 and you could have a Wagon or Sedan in 5-Speed Automatic or 5-Speed manual. Just remember, if it's running good when you buy it, immediately change the timing belt and pulleys, and check the oil feed line banjo bolts for those little filters, otherwise you'll be looking at $3000 or much more to fix it.
Also, as a helpful hint, leave the boost alone. Turning up the boost without investing in better piston is just begging for ring land failure. The bottom of the factory pistons are very thin, and even a couple of psi of additional boost is enough to cause uneven movement of the piston in the cylinder wall, and that spells death for these costly engines.
The All Wheel Drive system is practically bullet proof and the Legacy GT is more comfortable inside than the Imprezza because there is more room. It's ever so slightly bigger than the WRX which gives the Legacy GT a better ride and a little more neutral handling in the twisty bits. I would be remiss if I didn't at least mention the Legacy GT Spec B, which has several features and upgrades over the standard Legacy GT, like Si Drive (which is some kind of witchcraft sport mode setting), and bilstein struts, as well as VDC again more witchcraft.
While the Spec B variants are going to be more costly because of rarity, and because current owners are converted fanatics, there are other options. In 2008 Subaru brought the 3.0 Liter 6 Cylinder Boxer to the line up in the Legacy 3.0R Limited variant. Unfortunately it was only available with an automatic transmission, but it is a fair performer and has fewer potential issues than the Flat Four. The 3.0R isn't as common as the Legacy GT, but they are also not as expensive. A really good example of the 3.0R can be had for $5000 to $8000, as long as you're prepared to shop.
The H6 3.0 is a torquey beast and smooth like butter.
With all of these cars, even the 6 cylinder versions, there will eventually be head gasket leaks, or valve cover gasket leaks and if left unaddressed, you're looking at catastrophic failure. The head gasket replacement charge on my 2005 Legacy GT 2.5 Turbo, at a Subaru dealership was $1800, however my heads did not need to be machined so that saved me $500.
And if you hear any growling at highway speeds, just go ahead and replace all four wheel bearings. They have a short life and should be considered a routine maintenance item. New bearings front and rear can be had for around $250.
The 5-Speed manual variants of the Legacy GT have a BMW-esque two piece flywheel system that is supposed to eliminate some vibration. It's crap, and if you're changing the clutch assembly just buy a 2006 WRX single piece flywheel.
Yes, if you find a good running example, it can be a great performer On The Cheap, just approach with caution and take your time shopping. Also, set $1000 aside for maintenance.
If you find a Legacy GT for sale with any, and I mean ANY engine issues, just know that you'll be spending upwards of $5000 to get it back on the road and reliable, so buy accordingly. If you can buy one with a bad engine for $500, then you'll be okay, anything over that starts to approach "good money after bad" territory.