Iodophor is ok, but as an Iodophor user I'm switching over to Star San. I'm convinced that Star San is a superior killer and has a better shelf life. Plus on top of all that, Charlie Talley (founder of 5 Star, makers of Star San) is an amazing supporter of homebrew, and an all around cool guy.
It's not exceedingly expensive, from midwestsupplies.com
Iodophor, 32oz= 9.95
Star San, 32 oz= 11.95
Both are used at 1 oz/ 5 gallons, so you're looking at $2 total difference.