When I was looking for some for my shed, I searched craigslist daily for the word 'pallet', 'racking' and 'shelving'. Ended up finding a small shop that was closing selling some for really cheap (5 uprights, 14 beams and decking for $180) compared to what I had been seeing. Bought some other shelves from a local guy that deals in used shelving. He's got a large area with pallet and boltless shelving. If you don't mind a bit of a drive, they guy I'm talking about is in Royersford, PA, i can send you his contact number if you want. There is also another place in Philly, and two others outside of Philly that carry it that I see is craigslist regularly.
I also had seem on Ebay that seemed like decent deals. Just do an ebay search and limit the results by distance.