I have donated to AmiKit, which I really like and have no regrets for doing so, and I have requested to have an easy install script that would optimize as many of its features and programs as are possible, to run on my A4000 w/060/50MHz & 604e/233MHz, but its author has not agreed to provide such an optimization and script and has left that task to others, which I regret, but accept that he has other priorities in his life and I appreciate what he has done to create and maintain AmiKit, the best, or one of the best enhancements of the WinUAE emulator program.
I will probably check out AmigaSYS some day, which does have an optimized version for Classic Amigas. I have also checked on the progress of volunteer efforts to create a Boing Bag 3 for AmigaOS3.9 installations. But to answer the original question, Yes, I would probably pay $100 for an update to AmigaOS3.9 for 68060 Amigas depending on what was included with it and how it was provided. I don't see much sense in creating it for stock 68000 Amigas, and I am skeptical that it would be worthwhile on anything less than a 68030/40MHz, or 50MHz w/68882 and at least 32mb of Fast RAM.
It would have to be a step up from what is available already in several different places (mostly for free) and it would have to have a good install script so that I would not have to fight with its installation for days, weeks or months.
I could see it taking advantage of and being bundled with the IndivisionAGA4000 and Deneb cards to make a very useable and fun again Amiga, but then I am one of those old timers that still believes that a lot of fun can still be had with a fast 68060 and/or PPC accelerated Amigas.