What is a good flat iron that is around 30-40 dollars?

I really need to buy a flat iron but it can't be that expensive like a chi. my hair is naturally pretty straight but it just waves in a few places which is annoying. I want a flat iron that won't damage my hair too much. also, if you know of any good flat iron protective sprays that would be nice. right now i am using the chi iron guard but i don't really like it.