You have to remember about the level system in there. If you want to buy something decent (not price, i'm talking power/tuneability) you need to level up. The only cars available at lvl 0 are powered up to about 180-190 bhp if you're lucky.
When I was looking with my 20k, there wasn't much choice for my taste. A couple of FTO's, a mazda MX5, a Mazda 6, amongst the rubbish.
I bought a 1976 Golf GTi and had quite a bit of cash left over for a turbo + other mods to get me started. This gets you through quite a few races (Sunday Cup, FF cup, Hot Hatch Cup, Classic cup) in the beginner section of the game.
What I should have done was do the B license and some of the special events (I think you can do these without owning a car) This will get you up to lvl 6 or so and will let you get a nice 90's impreza or maybe an RX7.