They charge what they charge cause we pay it. The mark up on tires is nothing compared to the markup on the high-end engines(OS Speed/Nova, lol $400 really?).
Sweep tires are really good, and when you consider they are $45 for a set of 4 mounted, best tires on the market. Its amazing that more people dont run them. I still buy aka and jconcept tires, but only when they are on sale/bogo. My laptimes arent any faster nor do they last any longer. Its just nice to have a selection to help dial in on varying conditions.