I have a Cougar Pro and purchase my blade on ebay. As long as they are Roland style, you should be fine. Differences in prices depend on quantity, quality, item location, and seller. Not sure if I'm allowed to post links, but I've purchased from the seller below, here you can get 3 of each blade and a spare holder. I have different holders setup for the different medias I cut so that I'm not spending a bunch of time figuring out blade angle and depth each time.
http://www.ebay.com/itm/New-14mm-Blade- ... 1e8724d425