Aficionados--aka people who make a living playing guitar--may scoff. Surely, Charley's Guitar Shop on Royal Avenue is the place to buy a guitar in Dallas. Maybe so, but we don't have a grand or two lying about for a custom-made, and booking agents aren't lining up to offer us paying gigs for an off-key, painfully slow version of "Amazing Grace." So we're happy to shop at Guitar Center, the Wal-Mart of music stores, with its collection of about 8 zillion guitars, from $99 entry-level axes to vintage Gibsons and pricey Paul Reed Smiths. Here's why: bought a new Telecaster there (we rock on "Amazing Grace"). Guitar had problems. Took it back, without the receipt. No problem. When the store didn't have the same model to swap, the clerk, a very cool guy named Jacob, offered up a different model that cost $150 more and let us have it in exchange without paying a dime extra. "We want you to come back," he said. In fairy tales, retail and massages, a happy ending keeps you coming back for more.