Several questions about digital picture frames - can you help?

How much should a 4×6 or 5×7 photo frame cost? What’s the best place to get a deal on one? I’ve looked on amazon.com, but it was really hard for me to sort through everything. I looked at bestbuy.com, but there were all $80 – $100, and I just can’t afford to spend that much. Is it possible to find a 4×6 inch digital photo frame for under $50 at all?