Am I infringing on patents if I were to sell a product that I made from off the shelf components which are already patented?
The patent status of the components is not at all likely to play a role in the analysis. Have you put them together to implement a patented thing? If so, you have made a patented apparatus. I saw a picture a few years ago of the first working prototype of the super soaker. It was cut pieces of PVC tubing, an empty 2 liter coke bottle and lots of parts from a hardware store. New things are often made of old things put together in a new way.