This is actually something that crossed my mind. But I was trying to find a balance between simplicity and this kind of model.
Basically for me, the ideal situation would be to have a rep based up/down vote (like like/unlike everywhere is). And then have also a agree/disagree rewards system, in terms of a "donation" method, to represent the weighted (similar to your proposed bidding system) method of rewarding the post.
The difference here is that the "liking" of the post would cap the possible rewards in a exponential curve. The liking is also weighted itself... so if many shit accounts try to game the system, they will have little impact on the liking game.
Distributed rewards would be reduced if the post is disliked more than liked... and vice versa.
For the user, two buttons instead of 1... but the second (agree/disagree to rewards can be somehow automatic, depending if you like or dislike to make things easier).