A decent sewer camera with minimal features will run you at least $3000. The $300 cameras you're looking at are about 30 feet long and a cheaply made cable. If you're not worried about wasting $300 if it breaks easily, have at it.
For a bore scope, however, to look inside walls and tight spaces, I recommend this one.
I owned the Milwaukee bore scope and the Rigid one. Both broke in less than a year. The Milwaukee bore scope fiber optic cable cannot be replaced. So if it breaks, you're out $300.