As I said in a different post but also about RadioShack selling Arduino, it's not about the price, it's about the exposure of arduino to people that never heard of it. You know arduino, move along, get a clone or something as your second arduino. But to those in the dark, arduinos at radioshack will bring them into the light, for some extra dollars, of course.
The shame of it is that they are in the business to just be in the business whereas others support their product. I bought a soldering iron there that was too big to do through hole soldering. The prices there are an example of gouging. Their parts drawer has not been restocked at my local store for months. Mall stores don't carry a full line of parts because you have to go to a strip mall for that where they have 4X the number of part drawers. Most of their cashiers are clueless when it comes to doing anything with microcontrollers. They don't have a good answer for what Arduino is and it will be the day when they have a table with someone teaching Arduino in their stores.
I study prices and I can get the stuff cheaper online. The only way I would buy from a Radio Shack is if I was desperately needy for a part.