I've never bought any of those kits, just built several walkers, quadrupeds and
hexapods, from scratch. As I mentioned, it would be much easier with "any" kit
than from scratch. I like the Bioloid systems, as they allow you to try out different
designs, but never wanted to spend so much money. Bipeds, in general, are much
harder to build from scratch, as there are many torque and stability problems to
solve, so I would probably go with a kit for a biped.