I don't think you understand how consumer technology works. Right now maybe one of these screens cost ~$1.00 each for advertisers, and $0.10 for the manufacturers. If the popularity of these screens grows, advertisers will press on manufacturers to lower their cost (to allow themselves greater profit) and manufacturers will invest in lowering their own costs to lure business away from their competitors. As volumes increase, manufacturers will also be able to bring costs closer to the actual per-unit cost, since they can still have sufficient profit to recoup the sizable upfront R&D costs.
No, the advertisers will not magnanimously decide to decrease their profits in order to make the technology cheaper. But the nature of technology is that more widgets == lower cost per widget. If it gets cheap enough it may become affordable for less profitable ventures than advertising. How else do you think libraries, one of the most underfunded and neglected public institutions around, will be able to afford this? Or universities, whose endowments/funding are getting slashed in the current economic meltdown?
Lastly, despite your smug use of "capitalistic" as a pejorative term, the fact is without "capitalistic" folks investing in technology none of us would be here on this website having this discussion.