Surely this has been thought of before and maybe even discussed on here - Why does Google not provide Adsense Publishers with a minimum bid or a reserve bid?
Basically the idea is simple: publishers would provide a minimum price per click they are willing to take for giving up a visitor.
I know it is a not that easy and there is a lot of impact such a decision would make...mainly, advertisers would probably be paying more and inventories would shrink, to some extent. However I think the market would eventually balance things, i.e. if advertisers back out publishers would lower their minimums. It also works the opposite. If a site has users that are converting and high quality then a publisher could push up there minimums until they find a price advertising are not willing to pay.
Personally, it irks me when I see I give up a vistor for .08 cents. This is not always the case, but a good portion of advertisers have no problem bidding .10 a click and sitting back and lettting the power of Googles billions of impressions still provide traffic. I would love to set a minimum.. maybe .25/click. If an advertiser is not willing to pay that, then fine, show a PSA. However I know in my niche there are hundreds, if not thousands of advertisers that pay .50 or more.
I am looking for an intelligent discussion on the pros and cons of such a move. I know it will never happen, but it is an interesting thought.