I built a 13' wood frame, non-folder SOF (Yost style) of my own design this winter. Using scrap wood I built it cost me less than $180. Most of the cost was for the 18oz pvc coated fabric.

I also built an 8' long SOF of similar construction for my 2 year old. It cost me $75 using scrap pine, plywood and clear pvc.

Building a cheap stripper should cost less than $500. The wood is the cheapest part. Figure $20 for wood using local pines/firs (white pine for me). The fiberglass and epoxy makes it expensive.

Stitch and glues are similar. You can use cheap luan plywood but you get killed with the epoxy and glass.

My $0.02.

Dan