The cost of equipment and facility depends on the size of the space, the type and quantity of equipment, the location and the whatever your overhead costs are. As for charging trainers to use your space you pretty much have a couple of options:
Either one can bring a good revenue for you, but you will have to decide which one works for you. Personally I would go with the monthly fee (it’s very simple and easy to implement). But, I’m sure by now you must have already figured it out.