Straightener help ASAP please!!!!!?

I have medium/long hair length that's decently thick, doesn't do well in humidity, and frizzes very easily. I don't straighten my hair very often because every time I do it ends up losing it straightness in a couple hours. I'm looking for a cheaper alternative but one that still gets the job done very easily. I was looking at a Remington or Andis for around $20 from Target but if anyone has any other suggestions feel free to tell me. Any help or advice would be much appreciated!:)