I'm just wondering what others pay for commercial kitchen rental space. Not a bakery, just for custom orders.
Also, what does it include-- ovens, refrigeration, storage space, mixers, etc?
To find out the best answer to this you should research locally, not globally on here.
And the quickest way to find out is to contact a local commercial broker. They have all the information. You can also find out a lot by searching online for commercial real estate for lease and then your local address. I found Cityfeet to be a good search for both lease and for sale.
A few of my students found the cheapest way was to rent space from social service groups (VFW, Knights of Columbus, etc) that have large clean kitchens which are only used for special events. School and churches too, have kitchens. One student barters, the others pay $10-$15 per hour.