Autotrader.com
That's an autotrader search nationwide for a 318is. As you can see, your hard bent on finding anything near your limit, unless you want one banged up? Then still come the maintenece issues as ALL others have mentioned. It's so true. My car cost me $20k when I got her, and to date have dished out
$5,144.57 in repairs,
NOT including maintence stuff (yea, I had to calculate it twice to be sure

). So that's more than twice what you can afford. And that shit I paid out over the past three years, and this car is only 7 years old.
Save your money bud. The money you save while buying something more affordable for yourself, you can invest it, stick it into a high interest account, CD, stocks, etc. Give it a few years, then you can afford something more suitable.
Here's another autotrader search:
Honda Accord, Nationwide from 1981 to 1991
Goodluck,
Dough