My LHBS was able to order me a 50lb bucket of PBW for $165. It's a new store, so he's not getting great deals from the suppliers yet. Last time I bought that size bucket was quite some time. (think years) But, I only paid $120 at a different LHBS.
Anyway, even at $165, I figure it's a great deal. The problem with having that much is you tend to over use.
If you store can get it, and your wallet can handle it, I sure recommend going this route to save some cash.
(sorry if this is the wrong list, I don't see one for "cleaning supplies")