So much for being an early adopter. Just a week after the G1 phone went on sale for $179 at T-Mobile stores, Wal-Mart (NYSE: WMT) will begin selling them at a $30 discount at 550 of its locations—though no specifics on which ones. The price cut applies to new customers as well as existing customers eligible for an upgrade who sign up for a two-year contract, reports Dow Jones (NYSE: NWS).

Selling the phones at Wal-Mart is one way to get the phones into the mass market, though Peter Chou, CEO of HTC, the maker of the G1, said sales were better than initial projections. He expects to sell 600,000 by year’s end, which some believe is a deliberately low forecast.  For T-Mobile, selling through Wal-Mart doesn’t matter so much since they still get the contract. Wal-Mart, though, which has been selling phones for a while, gets a hot phone, one that can arguably draw customers to its stores. But the G1 also gives it a way to compete with Best Buy, the big box retailer which sees the wireless space as one its biggest and best future opportunities. Best Buy has been pushing hard in the wireless space. It has invested heavily to roll out the “Best Buy Mobile Experience” in all of its outlets as well as opening a number of standalone wireless outlets called Mobile Life stores. Currently, it is the only big box retailer to sell the iPhone (though there were rumors that Wal-Mart would too). Consider as well the news today that Wal-Mart is reducing the price of its music digital downloads with top hits going for $0.74, compared with $0.99 at iTunes, and starting at $0.89 at Amazon (NSDQ: AMZN). In the light of Best Buy’s September acquisition of music download service Napster (NSDQ: NAPS) in which it said it was especially interested in its mobile capabilities, it wouldn’t be too much of a stretch to see the G1, especially, somehow being bundled with music. The iPhone, of course, might be more difficult given iTunes, but still not unthinkable.