I buy most of my Legos these days second-hand from a huge online market called BrickLink. People post their inventories for sale, and you can order from all of these people. BrickLink manages all of it.
Well, one store (so far) is a generous donor in the Buy Me a Lego campaign, and I wish to mention them specifically.
Front Range Lego, has chipped in with a great donation of $5.00.
Not an insignificant donations. If you need to get some Lego bricks on the cheap, go check them out.