AFAIK, Best Buy put the sim in about 400-500 of their 700 stores, based on the stores' performance. They want to move a lot of units and they went for their "hottest" stores. They got their first shipment on June 4, but it takes them about 2-4 weeks to actually put products on the shelves. Sorry about that!
If your BB branch doesn't carry it (yet) then you can order it online from them or Amazon.
We'll have some more good news about the availability of the sim in additional (and exciting) chains.
/Admin