This is a video on how to put a 16 ft balance beam together for my daughter for $35. Having a beam at home has really helped :-)
No power tools, just hammer, nails and materials. I used: two 4x4x8 beams, two 2x4x96 inch beams, 4 metal fasteners, an old mat for padding (you can also use towels, cushions or netting, 3 yards of micro-fiber material, tape, hammer and nails. The process took about 45 minutes. You can make 8 (use only 1 4x4x8) , 12 (have one 4x4x8 cut to 4) or 14 ft (one 4x4x8 and one 4x4x6)