Best Buy preys on the 'I need this cable in 30 minutes for the big presentation' customer, and prices accordingly. Try buying coaxial cable - it's obscene!
The main reason I buy cables from Amazon instead of Monoprice is Prime. Monoprice's shipping is always slow for me. (Last gig I was at, we bought a truckload of their monitors, though, on my recommendation. Love those guys, just wish they could ship faster without ruining my wallet.)
Another commenter mentioned that Monoprice's HDMI quality has declined; I haven't noticed any problem with their Ethernet and USB cables.
For HDMI, Monoprice goes all the way down to $2: http://www.monoprice.com/Search/Index?keyword=hdmi
Best Buy preys on the 'I need this cable in 30 minutes for the big presentation' customer, and prices accordingly. Try buying coaxial cable - it's obscene!