Just me, but I think I'd look to rent elsewhere if at all possible (unless borrowing from someone I know). I have rented from a car company who kept records so poorly that when I returned the car they couldn't find any record of me having rented it and then asked how many days I'd had it. While that instance worked out okay (and was thankfully reserved by my employer) there was a lot more squishinness to the situation than I'd like .....
If there are no other alternatives, then I think I'd look at the rental rates for a similar piece of equipment from either Sunbelt Rental or United Rentals and offer less (perhaps much less depending on the situation) than that just due to my having to price it out. Which to me also raises questions as to whether any support would be available if the equipment experiences a failure while I'm using it, and if transport is available or if I'd have to supply it. Basically every service they offer that isn't contractually included in this offering a rate rental would be reason to reduce the rate I'm willing to pay .....
Have had fittings/hoses start leaking on equipment I've rented before (a 9,000-10,000lb excavator). Was simple enough to troubleshoot & fix once the rental place mechanic showed up (the extra set of eyes and a wrench larger than any I owned were needed to fix the issue).
That's just me though..... ?