ZeeAll 3 of my coops (#CohereCoop, #ZincCoop, #FifthPlaneCoop) are producer coops.
Cohere generates 6ish figures in revenue annually through professional services and SaaS sales/subscription. It's been profitable from the start (I converted my old solo consultancy) so member buy ins weren't necessary to fund operations; so we keep our buy in pretty low. ($2k, IIRC)
Fifth Plane generates 4~6 figures via dividends in the shared assets (it is the holding company for a bootstrapped startup that transitioned to employee ownership, but has no other activities)
Startup costs were minimal (higher than necessary... that was my bad) so member buy in is $500/member, and members are eligible after spending 2 years working at the subsidiary.
Zinc generates 3~4 figures. Member buy ins were used to fund operations as we explored revenue models; but which were ~$2k IIRC.