Hello.
Corsair CX500 $49.99
You can even go as low as
Antec VP-450 $34.99. I would recommend you not to take the PSU lightly as its an important part of your PC. Low quality PSUs can do serious damage (you can easily see that just by googling). Antec VP450 is nice I guess, but CX500 should be far better.
edit: I never use MIR on my suggestions, cause people usually don't want them. If you want to use them, then the prices will go even lower...