Maintenance Contract Quote

I have a potential client with a rather extensive existing surveillance system(smaller correctional facility), who is getting quotes for labor to service it's deficiencies. Typically we don't come in and do work on larger pre-existing systems that we didn't have a hand in installing, though of course we do have a standard hourly rate for labor. When giving a quote of this nature, is it customary to give a "per technician per hour" rate? What sort of method should I use for putting together a good rate for something like this?

You could give them X amount of Service hours for X amount of dollars and then any additional hours will be at the discounted rate of X per hour. Parts get a discount because of Service contract.

They pay you for the X amount of service hours monthly if they use them or not.

Generally on a system that was not originally installed by us we would charge a flat rate for maintenance to a 1-4 camera system. Then just add a further flat rate charge per every camera after that.