where is a good heat transfer company to send my designs for my heatpress

Depends on what kind of heat transfers and what color material you want to put your designs on. If you want to use dark material, plastisol transfers would be good, see transfer express and a few other vendors on the left. For other heat transfers just about anyone can do them.

There's a great list of places to get transfers here: http://www.t-shirtforums.com/plastisol-transfers/t77081.html