I'm used to working with bacteria - some of the more common laboratory strains sometimes come with an order from some vendors. What's the most convenient source to order common straings of Saccharomyces for lab work?
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.)
ATCC is the place I would go to, just like purchasing cell lines or bacterial lines. The reference ATCC catalog numbers are also listed with each of the common strains you have linked. Depending on the purpose, you could just go to your local grocery store for baker's yeast.
One very important resource is EUROSCARF. http://web.uni-frankfurt.de/fb15/mikro/euroscarf/
It is one of the very famous and dedicated strain repository for yeast (S. cerevisiae) strains. You can even find some very useful yeast plasmids here.
Another resource I would recommend will be the original labs, which made the mutant strains/plasmids. Yeast researchers as a community are very nice, I have almost always obtained the strains and plasmids that requested from the original labs.
Hope it helps, Cheers!!