In my experience ebay is rarely the best place. anyone savvy enough to be selling on ebay is going to look up lenses and find out what they're going for, and price for a fat margin. KEH is fantastic if you have a specific lens you want. As it has been said, CL is absolutely the best. When people find a box of lenses in their aunt's attic, they throw them on CL because its free and easy, and they have no idea what they're worth. I've gotten a nikon 50 1.4 ais for 30 bucks, 105 2.5 for 50, and an 80-200 push pull for 175$. the key is to check often and never be in a hurry to find a lens, wait for the deal to appear. I'd been wanting those lenses for a while and could have spend 5 times as much if i was in a hurry to buy them. patience is key.