BENTONVILLE, Ark. ( TheStreet) -- As if it isn't enough that Wal-Mart Stores ( WMT - Get Report) is a near monopoly for almost all things retail, it is now expanding its reach to include wireless cell-phone plans.

The behemoth discounter announced on Wednesday that it will begin offering two no-contract wireless service plans.

Straight Talk, which is a partnership with TracFone, a unit of America Movil ( AMX - Get Report), will offer two plans for either $30 or $45 a month and will be available at more than 3,200 Wal-Mart locations starting on Oct. 18.

According to Wal-Mart, the average adult spends $78 on their cell phone bill a month.

Cheaper prices could, of course, take market-share away from carriers like Sprint Nextel ( S - Get Report), MetroPCS ( PCS), Virgin Mobile ( VM) and Leap Wireless International ( LEAP), which offer plans for about $50 a month.

Retailers like Best Buy ( BBY - Get Report) also offer no-contract cell phones in stores.

Wal-Mart began testing the program in 234 stores starting last summer.

-- Reported by Jeanine Poggi in New York

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