[metasj]

At the least you need storage for the content ($10-20), and a physical device to read it off of ($20-40). If your community has lots of computers with no wireless antennas (old servers), USB keys that can be passed around make sense. If you have lots of mobile devices with wireless (phones or tablets), a hotspot like this makes sense and can be used by dozens of people at once.

In practice USB keys run a slightly higher risk of being wiped and repurposed for personal storage. Some IIAB users glue the SD card into their socket for that reason, making it take a lot longer to swap out.