ISO Saff-instant yeast
I can order it from King Arthur Flour in Vermont, but has anyone seen it for sale in the Boston area?
I used to get it at Costco's - that was about four years ago. Since I don't have a membership there anymore, I tried B.J.'s in Revere. They carry the same thing, only Fleischman's. Two lbs (separated in one lb packs) for about $3.50 - maybe a little more (including the added charge since I'm not a member).
I keep mine in the freezer. These days I bake nearly everyday, but for awhile I only made bread occasionally - and it still lasted until I finished all of it!
I'll never buy that expensive stuff in the grocery store again...
If you store that bag in your freezer, it will keep (literally) for years. That's what I do. In my experience the yeast remain very active far past the use by date when stored that way. I can't remember the last time I bought those ultra-expensive (for the amount) packets of Fleishman's.
One more local yeast factoid: If you ever have a hankering for some fresh yeast without going begging at your local bakery, Arax (in Watertown) usually has it in blocks that are around the size of a stick of butter. Since it is quite perishable, it is best if you have several recipes to make or bake a lot or have a friend who would also want some.