I bought a travel iron from wal mart before we left. Funny but the smaller travel irons are more expensive than the regular irons. Mine cost 18 bucks. Even funnier was the fact that I didn't need it. My stuff came out fairly un-wrinkled as I packed our formal/dinner clothing in my garment bag. Buy yourself a good garment bag instead of a travel iron.
My cabin attended told us in her little "welcome" speech that travel irons are discouraged onboard but if you brought one please be careful with it.