In the Florida Float Flyers' website, we list all the manufacturers of foam floats we can find.
Well, almost: there's Plane Fun floats yet to be added. ( http://www.geocities.com/planefunfloats/ ).
The rest of the links are scattered around on the table on the first page of the website.

Foam floats are best for performance. If you want scale looks, there's a link to SeaCommander floats. THese are pricey, fiberglass, and beautifully made. Built-up wood floats are available from Tower, BalsaUSA, Goldberg, etc. and make a good place to store water.