Sara, they're really super easy to make. We used a larger board than a lot of you girls would need only because I am heavier set, and we used steel piping that we had around here on the farm, I'm sure any hardware store could point you in the right direction for that.
The only thing that MAK's board has that mine doesn't is the ridges. The ridges on the ends would be a good idea so you don't go flying off if the roller gets to far to the edge, but so far that hasn't been a problem for me. As far as the board twisting on the roller, yea, it happens, but to me, I see that more of a challenge hehe. It's like a skateboard with one huge roller in the middle.
I would definitely suggest a fit ball (balance ball) and a balance board, they cant hurt, right? I have a riding lesson today, we'll see how well I do after practicing my post and balance all weekend long.