Sign up for your 7-day eMusic trial, and you get $10 download credit! You will be asked to enter credit card information. But once you use all $10 before the 7-day trial is over, you can cancel your subscription. You MUST cancel before your 7 days are up or you will end up a paying member. If you have a prepaid card with a zero balance, you can use that for your credit card information so that if you forget to cancel your subscription, it won't be charged.
I was able to get a couple of songs I couldn't afford on Amazon with my $10! They also have a lot of artists Amazon or iTunes don't have. What can I say- I have weird taste in music!