e-bay? Tons of sidekicks, Razrs, Motorolas. Make sure if the phone isnt branded with the t-mobile logo that it is:
1) Unlocked for use on their GSM Network (most old AT&T phones will NOT work)
2) operates on their primary frequency = 1900 MHz / secondary band is 850
3) accepts a SIM (subscriber identity module) card.
ANYWHERE a Cingular/ATT phone will work, a T-mobile phone will work and visa-versa. They are both GSM/GPRS/EDGE service providers and they have contracted use of each-others towers. Dont listen to the nonsense about them not having any signal. Unless you live in BFE you will be able to use their service. Go to http://www.t-mobile.com/coverage. They received KUDOS from Cnet, CNN, and MSNBC for being the MOST HONEST carrier when showing their customers the coverage available. T-Mobile is doing MORE for their customers and you wont believe what they have in store for the Mobile world AND your Home service.