most LFS's don't deal a lot with planted tanks, especially the high light, co2 injected ones. its a niche of the aquarium hobby, and the small LFS's have a hard enough time competing with petco, petsmart and wal-mart...they cannot afford to carry a bunch of regulators and CF fixtures.
I know i know more about plants than the owner of my favorite LFS...and unfortunately 90% of what he can order for me, I can find 25% cheaper online, including shipping. But I buy from him when I can, and keep a good relationship with him. I was able to get 4 bags of flourite for $15 a piece when I setup my 75gallon tank. SeaChem had a retailer sale, and he ordered extra bags for me since it helped on his freight charges.