Check the backyardbowyer on youtube for loads of PVC bow ideas.Yes I would think one of the DYI PVC homemade bows would be a fun project. If it gets wet or beat up no big deal. If I had a place to shoot I would make one. I think you can build one pretty cheap. When you find a good plan let us know. I might build one too.
You don't want anything with too much draw weight as you will tire too quickly, I recommend under 40#, nor should the bow itself be too heavy.What are some other OLD compound bow that I should be looking for?