The _Saccharomyces Genome Database_ has a list of sources here. One of them is the _Japanese Yeast Genetic Stock Center_ : I checked their site out and found that they charge ¥390 per strain which is around USD4. There is also a USD5 fee on all orders. I searched for a couple of standard strains, and these were in the catalogue, so it looks like a good possibility.
(Incidentally I have used USD here rather than $ because there seems to be a bug when typing that symbol twice in a post - try it and you'll see what I mean.)