Building a trailer and need some tips and prices on metal?

I'm not sure of your bargain considering the amount of modifications necessary, but it will be a great learning experience. Depending where you live, there may be a metal recycling place for your metal needs and the prices depend on the current price of scrap. I got a folding 4' X 8' trailer from Harbor Freight that was $280 as a kit and ran another $70 for the floor, fasteners and rails I made. The floor is 3/4" treated plywood and made for a great stiffener for the trailer frame ($35 at Lowes).