Where can you find cheap xbox wireless controllers?

I have two that need replacing, we have to tape the rechargeable batteries to keep them secure. I also need an extra to add to a system so gamestop will accept the system on trade.

So I'm trying to find a few on the cheap...I've been looking at craigslist with no luck...

Help a cag out!

thanks!

Ebay.

Trade/sell board on here.

Thrift shops.

Pawn shops.

Friends.