Good manufacturer/market for clear (transparent) bricks and plates in bulk? I never realized how rare clear bricks are! I'm looking for an efficient way to buy clear 2x4 (e.g. 3001) bricks in bulk. On BO, BL, and Peeron there are very small lots and prices close to $1 and beyond per brick. On Alibaba there are some new compatible brands but they tend to mix random colors and styles, no pure bulk packs of the same brick in clear (white).

While I can patch together an order from the above, I'm wondering if there is a manufacturer that just sells pure lots of the same type and color so I can keep buying from them and not have it be a brand new search each time.

Or do any markets exist that unlike PL/BO/Peeron include competing brands rather than only Lego?
Clear 2x4 bricks might seem to be expensive because LEGO doesn't produce them currently (they stopped making them in 2006). However, a quick search on Bricklink sees them listed as cheap as $0.02 per brick, used, which is not expensive at all. Just make sure you look for the correct brick design - you want to look at 3001old.