We actually seriously considered using a WISP (wireless Internet service provider). Cruzio offers "Business Broadband"[1], with "50 Mbps typical download and upload speeds" and the sales representative suggested we use that, instead.
At the time (early 2015, I think?) Cruzio had just finished installing a wireless presence on/near the old Wrigley Gum building (now a business park). They visited our site, to see whether we had line-of-sight to their antenna, and Cruzio engineers concluded they couldn't guarantee service, due to some trees.
So, it fell through, for us, but working with Cruzio staff has always seemed like a positive experience.
I'm not sure what other WISPs exist, but that's our story.
