What is the best flat iron for both straightening AND curling?

I'm looking for new flat iron, and I would like one that can both straighten and curl easily. My hair is very fine, so I would prefer one with adjustable temperature settings. Also, I'm looking for one the best quality that I can get for $30 or less. That's a lot to ask, I know, but can anyone recommend anything?What is the best flat iron for both straightening AND curling?
I'm going to say the new Instyler Rotating Iron. It really does a great job of straightening ur hair without all the crimps and damaged hair. And since the iron rotates and it's pretty much a curling iron. I brought this 3 weeks ago and I love it and the results are great. It was just 14.99. Go to this website www.getinstyler.com or search it on yahoo. Rotating Iron.What is the best flat iron for both straightening AND curling?
Check this one out! http://www.target.com/Infiniti-Conair-St鈥?/a> I know it's slightly above $30 but it's worth it! Good luck!