Try amazon and newegg.com

by R. Proffitt Moderator - 2/22/12 7:47 PM

In Reply to: I want to install a 3.0 USB card by maggieanne60102

Sort by popularity and both .com's allow returns.

http://www.newegg.com/Product/Product.aspx?Item=N82E16815640001 is a fine example where you read the reviews where speeds on USB 3.0 are not meeting expectations.

If you are looking for speed, go with ESATA.
bob