Is it possible to buy a bulk of 1000s of basic bricks (mostly 2x4)?
The LEGO Store has the Pick-a-Brick service, which allows you to bulk buy elements, up to 999 of any one element apparently.

It's not necessarily the cheapest, for example 2x4's are GBP£0.19 each, so purchasing 999 of them would cost me £189.81 plus shipping - there's no obvious savings/discounts for bulk ordering.



As Refro points out, BrickLink might be a better option: the prices are more variable, but often cheaper than PaB, discounts for bulk purchases can be found from some sellers, but shipping costs might be higher depending on where the seller is based relative to you.