If you mean polystyrene balls, I bought them from Getaz Romang in Bussigny. It's a construction supplier, and the polstyrene balls are a form of insulation. The name in french are " perles de polystyrène".
its used as cavity wall insulation so look for a building supplier.. that would be the cheapest anyway ! if you are not bothered about costs then i have seen it in globus at mind warping prices
When you buy electrical appliances (and some other goods, also), they are normally packed in big chunks of polystyrene. If you look closely, you can see that the solid is actually made up of compressed balls.
In the evenings as you watch tele or chat to friends on the phone, you can sit and pick these balls apart (much the same as women sit and knit) ...... it's very relaxing and almost as satisfying as popping bubble wrap, or squeezing balls.
P.S. Thanks for the photos Verbier, I have been wanting to order some, but online they only have the dimensions, not the volume - so had no clue which ones to choose!