Piggs, Radio Sound had a decent reputation for repairs. It was a flat rate cost if I remember correctly. Whether you'd get hosed or not depends entirely on your failure that way. But if it's an amp you're probably being treated fairly.
If you decide, however, to go to some other radio contact HD-Dude here on this site. He's a dealer for aftermarket retrofit conversion kits and can offer a discount better than buying from the company's direct. The kits make many aftermarket radios a plug in replacement keeping all your handlebar controls in tact. I've installed a couple of them for friends in the area here. Not a bad setup if you don't mind going to an aftermarket radio.
Radio Sounds flat rate fee would be your cheapest repair. The aftermarket retrofit would be next. The new Harmon Kardon radio as a retrofit would be the most expensive and the most difficult. Don't start that one unless you can read the code in the radio, understand it, rewrite it, and write it back to the radio.