Yes we do something like that in the academic setting. Locals are billed for first 8 hrs at usual sem rates. Collaborators from outside pay for all 24… unless they collaborate so well that they use a locals account and we don’t know. Which is ok because the additional cost for outsiders covers work I have to do for them … image handling etc.
And a lot depends on how much of the service contract, consumables, and labor you must cover in your budget.
Downtime is another thing … we were going to have submitted projects that were unfunded but worthy, with a small committee to decide those likely to be successful.
Hope ghis helps