In the past, you could have someone with a postpaid T-Mobile account call/chat and ask for the unlock code. T-Mobile recently revised their subidy unlocking procedures so now the phone's IMEI has to show up on the account which makes it more difficult.
Your best bet may be eBay. Good luck!
Castrol EDGE 5W-30 is my drug of choice.
Toyota | moving forward
Primary: iPhone 5 (AWS), Lumia 521, and Exhilarate HSPA+/LTE (T-Zones line): 5 lines, 1x $15 4.5GB data, 3x $2.99 T-Zones (truly unlimited 4G data), myFaves, corp discount + $10/mo loyalty discount = $94/mo tax inclusive
Secondary: iPhone 3GS: Airvoice Wireless, Samsung Fascinate & HTC Trophy: Page Plus