Didn't see this rule, but it is a good one. In fact, I suggested this to you guys a year ago in that classifieds crowd funding thread wherein I said I couldn't pay for anything that isn't already produced.
@Brogan@Mike , regarding this, could I query if the following would be permissible:
Mentioning in an add-on discussion thread, for an add-on which is open-source and of which multiple people are requesting porting to XF2 (but the original dev says he can't but anyone else is free to), that I would be open to doing it for/by crowdfunding, with that crowdfunding organized off site (e.g. on my site).