I propose a market for points. No reputation is gained or lost in the process. Please understand what is being proposed before voting/commenting.
The transferred points are not added to the buyer's shown reputation points. They are kept separate and hidden from the public and do not increase reputation. They can only be used to pay a bounty.
The transferred points are not subtracted from the seller's shown reputation points. They are kept separate just to calculate how much the seller has left to sell. If the seller had 5k points and sold 1k he still has 4k to sell and still has 5k reputation.
There is a limit for how much one can sell, say a maximum of 20% of his points. In the above example the seller would not have anything left to sell as he already sold 1k which is 20% of his 5k points.
The points won from bounties paid with transferred points can not be sold and do not count for the calculus of the above limit. Say one had 1,000 points and won 300 points from a bounty paid with transferred points. He now has a total of 1,300 reputation but can only sell 20% of the original 1k points, 200 points.