I need info about using pvc or mdpv or hdpv for pontoons ???

I want to build a small two man pontoon boat, and would like to use inexpensive locally available items for it's construction...I have seen pontoons of this type, but do not know where to get the end peices, or how to mount my frame structure on them...Any ideas, or wholesale/salvage places that can accommodate me would be appreciated.. Thanks !!!