I did it on Ebay. Got the sim that was activated already, had something like 150 or 200 min on it, popped it in and it worked from day one. Called T-mobile up and asked to get a number change to my local area code, no problem. Most of the e-bay cards have a very fast expiration time, two weeks to a month, but you can keep them working with a recharge.

Beware of one thing with t-mobile prepaid, you don't roam to many other networks. If you are going someplace other then a major area, it may not have coverage for you.

I've been preapid only since April, I dont' think I'll ever go back.