RE: string cost
It's personal preference on what string material you use and who makes them. If you make it yourself then yes the cost would be between $4-$6 but the start up costs are more plus your time. If you want I made my own jig along the lines of the Yellowstone Dream Machine and have about $35 into it (not including string material). Hardest part was the posts (brother is a machinist so did them for me) but there are other ways to do them. If you want I can send you the instructions. As to the speed increase of almost 40 fps I guess I'm a doubting Thomas. Maybe you get some increase (not saying you didn't) but that seemed to me way too high.