You can also take some old heatsinks that you have laying around (or can scrounge), and cut them up yourself to your own measurements. Aluminum cuts like nothing. I even took some old cheap slot-cut 50mm heatsinks and cross-cut them to give more surface area before dividing them up.
Try http://www.mouser.com Then do a search for part# 532-501200B00.
These are small heatsinks, 2 of which will cover the chips on most video cards. They are a versatile option for lots of places, but you need thermal epoxy to hold them where you want them.