I have it and used it right after I bought it to make Drunkard's Path blocks and it does work.
I saw a lady on Simply Quilts using a 1/4" straight stitch foot (the kind with the little 1/4" guide on the side) use that foot the same way the Curve Master works. I tried it and it does work, also but the Curve Master is easier. It does take some practice so don't count on your first few blocks being the correct size. Allow for trimming until you get the hang of it.
Oh, and I paid about $30 for mine at the quilt show in Paducah 5 years ago.