Take a look at a cat trailer. You'll see how simple they are. If you have access to a cheap trailer you could buy channel or tubular steel for the cross pieces. You'll need some u-bolts, rollers, and rubber for the front cross piece which you can get from a boat dealer. I actually seen someone use 2x6 wood. Cut out some V's for the hull and that was his trailer. After buying the wood or steel it may end up costing as much as one already done. However, here on the midwest I think it would be nearly impossible to find a trailer without a boat. Especially now that you're looking for one.