How Much Is a Facebook Group Worth? How to Price a Facebook Group When Buying or Selling

TL;DR: as much as you can get.
The longer answer:
Facebook groups are an unregulated market. There is no market price and no rate card along the lines of “one user is worth X, a thousand users are worth 1,000X.” In the end, the highest price will come from the person you manage to show the most value to.
A few examples:
My late grandmother: she wouldn’t have been interested in the group even for 10 agorot.
My dad: he’s been hearing me go on about Facebook groups for a few years now, so maybe he’d offer a few shekels, or a few hundred shekels.
Me: I don’t run workshops, but I understand the business potential that could be there. So I’d run the numbers in my head: “How much is my time worth? How long from the moment I take over the asset until it generates revenue? How much will it generate? Say I’m considering buying the group for ₪2,000 (ILS). I’d ask myself what else I could do with ₪2,000, and so on.” Based on that, I’d make an offer.
A business owner who runs chocolate workshops: if you need to show them the value of the group, or maybe run a test with them and send them leads they close, your position will be much stronger.
At the end of the day, small business owners want to see the money at the end of the road. The further away it is, the less excited they’ll be. That means they’ll see the asset as less attractive and offer less money. The more they see dollar signs, the more they’ll offer.
The game is showing the business owner the value. The more value there is, the more it’s worth. And showing value takes work.
If you want to get 10K for the group, prove to the business owner that by buying the group for 10K, they get a lot more than the 10K they’d spend on paid ads.
Good luck!