What wireless USB network dongle will will work with a samsung C7000?

D-link dwa-140 should work fine.

Last time i checked, they were around $20-$25 on ebay, which is a lot cheaper that the Samsung rip-off dongle (which in essence, is nothing but a re-badged DWA-140!).

Make sure you check the version of the D-link DWA-140 before you buy. I bought the B2 ver 1.71 and can't get it to work on my Samsung tv.