I think as long as it goes on something physical that is needed and will make a long term difference, not paying for the actual work, we're not RetroArch or any of those other vile Patreon or Bountysource funded projects.
That's where I draw the line there personally, money into pockets is money out of the system and should be refused, money spent on items that will benefit everybody is not.
The $30,000+ a month into pockets you read about with other projects (including ones complaining that $7000 a month isn't enough) is horrible, the same amount spent on actual hardware would do wonders. That's why I specifically suggested it could go towards Game & Watch or similar.
Anyway, the way I see it, the work has been done, a payment is not required, but if the OP wants to donate $100 towards the purchase of some items that will help with emulation to say thank you, that is now a choice. We could pick up one of those LJN video art machines for hardware analysis for example.