SunSmile*2013 via eBay offers this 49-Foot 6-LED USB Borescope Inspection Camera for $16.11 with free shipping. (Select 15 meters in the dropdown box.) That's tied with our mention from two weeks ago and the lowest total price we've seen. (It's also a current low by $7, outside of other eBay sellers.) It features a waterproof camera and 640x480 maximum resolution.
Note: Allow up to seven weeks for delivery.