Adam, I knew we'd rope you into the BSC with our animated stories and charming pictures!
Shells are easy to find. Often LFSs will sell them or have buckets of them as hermit homes. You can also go to the Jersey shore and collect all kinds of rubble, shells etc. I've have collected from the Outer Banks and boiled the daylights out of it before giving it to Spotty. In fact, even if I get rubble from the bottom of the LR tank at my LFS, I always boil it to kill any nasties I don't want in my tank.
When you getting back buddy?