Sorry, I’m not familiar with the Boston area, but I might be able to point you in the right direction. I’ve seen the Feline Pine (FP) original pellet formula in just about every pet store, the clumping tends to vary, though the major chains (Petco, PetSmart, etc) usually have both varieties. Wal Mart usually just has original, Target typically carries both, and I rarely make it to KMart anymore, but the last time I was there I saw both kinds. You can also try your local grocery stores, I’ve found both forms of FP in Winn Dixie and Publix down in this neck of the woods. If you don’t feel like driving all over town, just call ahead and see if they have any… and you can see who has it for less. : )
