Selling merch on the road – whether your band has CDs and shirts or you run your own enterprising business in geeky goods as our contributor Liz McLean Knight does – is a big challenge. Buying a full-blown credit card terminal is expensive. That’s why I’m absolutely with Hypebot’s Virgil Dickerson: running credit card numbers on an iPhone is a game changer.

iPhone App Adds Mobile Credit Card Processing to DIY Toolkit

The application in question is called Innerfence, and Apple gets it, too, as they’ve added it to a new TV ad. The app is US$49.99, pricey for an iPhone app but a whole lot less money – and a whole lot more convenient – than a big, clunky conventional terminal. Right now, you also get a $50 gift certificate to iTunes, so you can catch up on LOST and buy the new Depeche Mode and feel like the whole thing is free. The back end is powered by Authorize.net, one of the major vendors of online credit card processing. Unlike Authorize.net’s tangled website, though, this is a beautiful, polished app that works the way you want. Ironically, it puts to shame the terminals Apple employees themselves use at the Apple Store. (In fact, it sounds as though Apple will indeed — unsurprisingly — replace those Windows Mobile-powered devices with iPhones, says AppleInsider.)

There’s no physical scanner, but for casual sales that’s probably okay.