If you need to connect more than 4 devices or need a wired Ethernet connection, there are low cost routers available that can use WIFI as WAN. They allow you to connect to a hotspot or wifi tether capable phone and connect wired and additional wireless clients to it.
I've been using a Cradlepoint MBR95 as backup, which works great...and can usually be found for around $99, easy setup too. I've run 25 or so devices on mine and it didn't have any issues...
