If you think about it a system that openly allows you to sell your vote is not as terrible idea as it may sound at first glance. It let's market forces make decisions.
1.The money spent on (mostly negative) political campaigns will find a better use in the pocket of a voter.
2.Voter participation will start approaching 100%
and many other benefits.
It also creates a whole host of problems. The purpose of voting is, in theory, to allow the candidate which would benefit the largest proportion of voters to be elected to an office (assuming winner take all system like the US). The problem with introducing money into the equation is that most people fail to account for the diminishing marginal value of money. For people who have very little money, the marginal value of money is very high, so you can "buy" their votes for comparatively less than people who are better off. This leads to all kinds of suboptimal outcomes whereby even rational actors will vote against their own interests. The reality is far worse, since most people don't understand how to value political platforms, and uninformed voters will follow the red herring of money offered for their votes.
The problem with voting that is divorced from property rights is that people will vote themselves other peoples money via theft.
A vote is a property right, if someone can vote for Obama just because he is black.... or someone else can vote without considering the issues... then why shouldn't someone transfer their vote to someone willing to pay them for it.
Votes are bought all the time... only they are bought with campaign promises to steal other peoples money to pay welfare and special interests. At least buying votes up front is being done with the vote buyers money rather than the money of the people who voted against the welfare.
So you see.. vote buying has been made into an irrational politically correct opinion rather than a rational realization that for the average person selling their vote to the highest bidder is much better for them.
For example: in my opinion there is no difference between the two major parties in the US and I know the process is rigged. Knowing that my vote is not even worth the time to cast it, I would gladly sell my vote because my life would be better by selling my vote than by not selling it.
If we wanted to have a rational political system it should require 95% voter approval and that approval would have to be BOUGHT. 5% error to prevent deadlock for those unwilling to sell at any price...
You may be able to buy up 90% of the vote cheaply... but to get the approval of those who would be harmed the most by a bill 5% minority... would be a lot more expensive. You would have a government with 95% consensus based upon property rights.
So if a bill was generally acceptable and not likely to harm people unfairly then the cost of buying up the votes would be low... if the bill was terrible (Obama Care) the cost of buying up the votes would be prohibitive.
I conclude from this that vote buying + super majority is a far better system than we have today. I would be compensated a lot more for all of the economic harm being done to me. This system would also work much better if laws required re-approval to stay in effect. This would allow me to set my "lease rate" on my loss of freedoms.
Those that hold out in the last 5% would end up having the law passed anyway and forfeiting an opportunity to be compensated for what ever harm was done to them.