58mm uv filter

So I just got the Canon Rebel T3i with the 18-55mm kit lens and I want a uv filter.

I don't want to spend too much money (over 45$) and under 20 would be great!!!

I don't need it to be anything special just something that if it gets a scratch I can throw out rather than live with a lens withe a scrape in every picture I take.

thanks