What is the maximum number of points one can leave as a bounty?
You can leave a maximum of 500 points for a single bounty, according to the help center. The page also says that you could offer multiple bounties on the same question (only one at a time though).
However, there doesn't seem to be any restriction on the number of times you could offer a bounty on one question (after the previous one is inactive, of course), so you could technically give away all your reputation, although in your case that would take a loooooong time. :-)