Just thinking over some numbers for using these for a marquee (backlit, obviously). It says they're about 3/8" cubed, and from looking at them, I'm guessing that size is center-to-center when they're connected. So if you wanted to make a marquee that consisted of a solid sheet of these, it would come out something like this:
Let's say the marquee is 36" X 9". That would be 96 blocks X 24 blocks, or 2304 blocks. The prices for the sets of blocks tends to come out to around 2 to 2.5 cents per block, so you'd be looking at $50 to $60, which isn't as bad as I thought it might be. If Stewart Toys got the 2800 piece set back in stock, you could pick that up for $46 + shipping, but it might not have the selection of colors you want. I think you might be better off getting the single-color 200 packs for $5 each and getting the colors you really want.
If anyone actually gets some of these, please let us know how they are.

Another cool pic: