You can make a set of floats for mere pennies, using styrofoam insulation. Here's a web-site.
http://www.flyinglindy.homestead.com/skisandfloats.html
These are good basic floats. Commercially available floats tend to be more detailed or scale-like.
Several float suppliers are listed on my club website: See the signature line below. We collected all the amassed wisdom of float-ology and stuffed it into this one website. One of these days I will re-organize it to make stuff easier to find...but it's there.