Not sure how many people would want to pay to do their own jobs.
As a positive incentive, a countering "attending" pool, also budgetable. Meetings with strong appeal would be compensated from that.
Not sure what to do with the Imaginary Meeting Points at the end of the year, though possibly use it as the basis of some sort of merit award or bonus.
For actually tracking Meeting Points, one option might be to make them a project metric? As in: "We predict our project will consume 21 Meeting Points, if we go over 25 that's a failure to be analyzed afterwards like overruning schedule or budget, if we're under 15 we're probably budgeting wrong".
I'm not saying the market/cost approach is necessarily the best or appropriate. But it's an interesting thought experiment to work through it.
Sometimes imposing arbitrary requirements (e.g., "have an agenda") is a cheaper way of effecting the same ends. Though Goodhart's Law is another pitfall.
NB: "vipers"?
Of course people shouldn't pay to do their work, so this must be taken from their allocated budget. If they don't have a budget they cannot invite anyone without the permission of someone who has a budget and think the meeting is a good idea.