In order to accurately determine which plumbing camera you should purchase, you will need to think about your project itself. If you know the issue with your pipes is deep in the pipe itself, you will want to make sure you buy a camera that is long enough to reach the problem area. Buying a camera that is even a little longer than you need is not a bad idea as you will give yourself some room for error in your judgment.
Once you have an idea of the type of plumbing camera you will need to complete your project, you will want to read through some consumer reviews to see what others are saying about a particular make and model. Buying a camera that has nothing but positive reviews will help increase your chances of being satisfied with your purchase.