most of the big craft stores have terrible websites. Michaels, hobby lobby, and joann all have no products online. (JoAnn is just starting to put a few things on, the last I checked)
All of the craft stores do have good BB ply, but you can't ask any one for it. They will give you stupid looks and wander around.
Some times it is with model making stuff, other times it is with the "woodworking" stuff. You have to ignore all of the laser cut crap for $0.99, but the michaels and joann in my area both stock a US made bb ply.
On a side note. I did some research going to the craft stores, Rockler and a lumber yard for BB ply and the prices at each. I can't remember the exact prices, It is probably on the forum someplace. The results were if you can buy a 5x5 sheet at the lumber yard that is the cheapest way to go (but the most "hassle" trying to transport and cut it) The craft stores sold a 1'x2' piece for less then Rockler sold a slightly larger piece. The 1'x2' piece is nice for me, I can get 2 portraits and a few ornaments for $3-4. The quality is as good or better then what I get at my lumberyard.