You can do what i did , i didn't make them pay in any of the setting up costs , i built everything and i have free electricity , after building everything i charged them 1/3 of thier profits to host the rigs in my place and taking care of everything and the offer was fair enough for them.
If you are doing all the work of both setting up, hosting, and maintenance that 1/3rd is more then reasonable. I'd not even consider going lower then that if I was in your shoes.
