Balance boards, wobble boards, bosu, balls all provide unstable surfaces for us to do exercises on, increasing the difficulty of the exercise, an forcing core muscle groups to engage (as well as improve neuro muscular connections so that things happen when they should).

There is no need to spend LOTs of money on some of these things. if you can't do certain exercises standing on one leg (including simple, standing on one leg), then you shouldn't be moving to unstable surfaces. (my own opinion)

have fun!

han