if you lease the building i would make sure insurance is part of the contract which it usually is. you are negotiating a short term lease so you want to think about things like how long you want to execute lease, how many days, utilities, security (if needed), rest room facilities & supplies, if items left overnight how secure are facilities. are you planning to just do this over the weekends, or have the facility available all week? will the crafters need to bring their own table and chairs or will you supply them? will the crafters need to pack up their stuff every time and bring back with them? just sme things to consider.
i am doing something like this for my sister circle supper club. so many of us sell crafts, sell jewelry, a couple of authors, sell candles so i am securing a site for us to rent & set up booths and then advertise by flyers and local papers to open to the public. we will only have our site for one day and they will need to supply their own setup (chairs/display tables).
good luck with your idea. there are many crafters that are looking for space to display their wares. many go to flea markets or craft shows but not all of them. just develop your idea and i am sure there are crafters in your area who are going to appreciate a venue to sell there wares.
there is a young woman in my city that does this type activity about 5 times a year and call it a woman's day out. vendor's buy booth setups and it is advertised to the public. it is very popular.