I bought 3 kids bikes at Value Thrift store at sun ray shopping center. I took the front wheels off and welded them on to short pieces of exercise machine steel that's the same width as my runners. The cost of this land yacht conversion was a modest $30 ( including welding)
I have the pedals spring loaded with 2 bungee cords. You can save lots of money by cutting & piecing exercise machine steel into useful accessories.