Well if you want to pay about 3 times what the belt is worth you can go OEM. Nothing wrong with a good after market belt. More often than not they're manufactured by the same company's that make the OEM belts.
Here, and like most other places and states ive been to, ive only seen an oem belt cost almost 20 more than a ultimax 3 belt. Even on my older sleds, a regular dayco worked fine but didnt last nowhere near as long as an oem and back then they were only 10 bucks more.