Yep, every radio shack in the U.S. sells 5-packs of 68 ohm resistors for 99 cents, which is two more than you need.

Simple guide:
http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html

There's another method that works with only one resistor but it requires you stick the resistor directly in the DVI connector itself, which I wasn't really comfortable with...