According to Wal-Mart, roughly 550 of its stores will sell the open source Linux T-Mobile G1 for $148.88 starting tomorrow. The device, the first mobile phone based on the Google Android mobile operating system officially went on sale Oct. 22 in T-Mobile stores nationwide.

Wal-Mart is offering the device at a $31.11 discount compared to the $179.99 T-Mobile USA is charging in its retail stores and online. Buyers who purchase the device at Wal-Mart are still required to sign a two-year contract with T-Mobile.

Wal-Mart spokeswoman Melissa O'Brien told Reuters on Tuesday that Wal-Mart wanted to offer its customers the "products they want at the very best value."

The G1, built on hardware from device-maker HTC, officially launched last Wednesday, going on sale at 8 a.m. local time at T-Mobile stores. Leading up to public availability, some reports indicated that T-Mobile had sold more than 1.5 million of the smart phones in an online presale. A T-Mobile representative this week would not comment on how many of the devices have been sold in T-Mobile stores.

"Pre-sales exceeded expectations and we continue to see robust interest from customers now that the phone has launched nationally," a T-Mobile spokesperson said in an email Friday.