@phred I was planning on keeping it open indefinitely - i.e., the amount slowly grows until it reaches a point where a developer considers it worth their time to develop, develops it, and gets the money.
I've also said I'm completely open to any other method or platform for organising contribution pledges, if you have any suggestions.
The overwhelmingly negative reaction I've got in this thread, though, is making me reconsider this endeavour. I'm simply trying to get a feature I want implemented, make the software that I love better for everyone, and pay developers for their labour rather than moan in an entitled manner for free stuff in the "feature request" forum.
I'm sorry, but I could, off the top of my head, think up several better "scams" than start a fake crowdfunding campaign for the development of a fairly niche plugin, for a software which has a middling amount of users, for a type of software (music managers) that most people don't use anymore.