I would expect for many developers it is really only a matter of how much you are willing to pay. If they don't already do freelance work then that cost might reasonably be higher than what it would cost to hire someone else to implement it because of the extra tax paperwork and whatnot that they now need to deal with.

Of course there will be some maintainers who are simply not interesed or unable to offer paid support (e.g. due to their employer being a control freak) but that's ok. As others have pointed out, forking / maintaining out of tree patches (and providing them to others) is not inherently hostile.