EAwakening via eBay offers this 6-Foot Waterproof USB Borescope Camera for $4.69 with free shipping. (Select "2M" from the drop-down menu.) That's a slight drop from last week's mention and the lowest total price we've seen. (It's a current best by $4, outside of other eBay vendors.) It records at 640x480 at up to 30 fps.
Note: This item ships from Hong Kong and may take two to eight weeks for delivery.