If you don't mind getting dirty in the hunt for a bargain, then you should consider a trip to Building 19 3/4 in Norwood. They have bits of everything in a great big warehouse setting.
Strangely, the grime in the store is part of their marketing scheme. When you leave you feel like you really need a shower, but that is part of the charm.
The samples department has some great buys, and the prices can't be beat on the bound carpet remnants - great for dorms or first apartments.