A defaulted student loan would mean that it is at a Collection Agency, right? If that is the case, no bank nor CU will be lending anything to you, regardless of the amount you are asking for, unless there is someone to co-sign the loan.
Legal loan sharks will take advantage of you at this situation, don't be shocked if you get quoted with interest rates of 25%.
With $2000 on hand and bad credit, I would look at new cars, not used. There are some new car dealerships who are willing to take higher risks. Ford, GM, Hyundai, Kia, Mitsubishi. If you put $2000 down on a lease for a $20,000 new vehicle, chances are you will get it. The dealer isn't taken a big risk, if you default, they will get their car back, and $2000 is more than 6 months of payments. Some dealers are willing to do that. Mitsubishi probally is more 'motivated' than others to do business at this point, leasing an 05 Lancer isn't a bad idea. Like Sterling said, you have to start making monthly payments NOW to rebuild your credit. By the time the lease is done, you will have more options for sure.