The rate will vary from region to region. Around here I’ve seen rentals for around $20/hour, with a one-hour minimum. The ones I’ve seen require completing a longarm class at the shop, for which there is a substantial charge.
I would search around the web to find places that rent longarms and see what they charge and what the rules are. Others’ policies will give you a good idea of what sorts of issues might come up. Just as an example, I found this one (
https://www.sewfabricated.com/module...classId=233980) (no affiliation), and it details which supplies they’ll provide and which the renter needs to provide. It also has a “mentor” charge if someone still needs help after the first rental.
Another thing to consider: how much could someone mess up the longarm if they don’t know what they’re doing? I don’t know much about longarms and can’t answer this question, but if someone could potentially do something to the machine that would cost a lot to fix, then it might not be worthwhile.