I pay for a Zoom account to run a bunch of meetings. It costs £14.39 a month, and we get up to 100 people. That's a lot of people. We get about 2500 attendances a month (between 20 and 70 per meeting). Ten attendances costs around sixpence.
We ask for contributions once or twice a year. People contribute a few pounds. That's it, and we're good for a few months or maybe a year.
There are organisations (e.g. retreat houses / retreat organisations) with full-time employees, infrastructure, onsite events, formal communications, mailing lists and administration, written handouts, technical enhancements, etc., where there will be registration costs for online events, in part because there is cross-subsidisation of face-to-face activities. I'm not talking about those. I'm talking ordinary Twelve-Step fellowship meetings and similar events hosted by people in recovery.
They're not expensive to set up, and you get a lot of bang for your buck. If people are asking for money, think about what the deal might actually cost and where any surplus is going. If it's not carried forward, and it's not being forwarded to an Intergroup or similar, ask questions.