I thought there was already a "deal" rule that the price couldn't be a permanent thing -- it had to be some kind of time-dependent deal. So the flood of constantly 2.99 books scenario is already prohibited (and presumably dealt with without our seeing it) by moderation.
Less Kindle-centric would be nice. B&N has an affiliate program, too. But I'm not going to spend all my day to help Strangers on the Internet if I can't be allowed to put out a tip jar.
I'd perfectly support a split between "free" and "under $5" if the forum got THAT busy. I'm doubtful of Worst Case Scenarios, though. Not for a buck a day payoff. Most people are not going to commit that time and effort for a Get Rich Quick scheme that won't.