This is a fantasy ... go offer some open source maintainer some money to implement something they don't want or care about and come back and tell us if it was simple. It may be in some cases where they are actively looking for that kind of work, but more than likely they will have no interest.

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.