Good pair of soccer cleats for cheap?

I'm a college student so I don't have much money. Sometimes, my friends and I go out and fool around a bit playing soccer. Problem is where we usually play isn't a field, so when it rains, it get really muddy and if you're not wearing cleats, you're slipping around. I figure it might not be a bad idea to invest in some cleats, but since I'm not doing this at a competitive level, I figure that I should get a cheap pair. Curious if anyone has any recommendations. I'm trying to not spend more than $50.