This is basically a rental service with a fixed yearly fee, so I guess they could draw up some sort of standard rental contract similar to the one that Home Depot uses. Maybe add some large ugly warning stickers, too.
Outdoor stores and the like rent sleeping bags all the time. Im sure you can rent something like a chocolate fountain from one of those party supply places. A basic fondue set (which you could probably rig up with what you have in a house) is likely too cheap to justify the overhead of renting. That is sort of the classic borrow from a neighbor if you can.
Do you never leave your house? You have never eaten off a plate you don't own? Never been to a restaurant? You've never slept in a hotel or at a friend's house?
(I went rouge and bought both dishes and blankets from Goodwill so don't come over to my house.)
Those are definitely two things I would not borrow from anywhere.