I think you can get them at Bumps to Babes. I had one called a Boppy pillow which I also got at B2B, it was very useful for me, though I don't know that everyone finds them essential.
I bought mine at Bumpt to Babes too. Good after c section but now my baby is 2 months old (and she is tiny as a premature baby), I find that somehow the pillow is too small. I BF mainly on the sofa, and the pillow seems to short fr the baby and too high. I am switching slowey for a normal pillow.