I think you should try calling gyms around your area and see if they are willing to lend you some space for rent. Im sure some gyms would love to increase their profit per sq foot by lending you some space that isnt being utilized properly.
I tried doing the sublet/rent space from an existing studio a few times. I always ended up getting my own space. The inconsistency of being in a shared space and the frequent time conflicts with others leasing the space was just an irritation. But it did give me the nudge to get out and do it on my own.
We are opening a exclusive private gym in Nashua, NH for the express use of independant trainers they would have full access for there clients at a flat monthly rate, no hidden cost your rates would be entirely your own. We offer a great location right near the pheasant lane mall
Very well equip and clean plenty of parking
For more info please contact Kevin McGaunn