It's a case-less board with a single 2.4 GHz radio but it really is $5 including tax and shipping and you can buy as many as you want.
They're estimated to ship in November.
I ordered 10 of them for mesh projects.
It's a bit sad that they don't have the ethernet broken out since that would make them useful as mesh routers that we could just hand out left and right. We could make ethernet breakout boards for them ourselves if we feel like doing some soldering, but given that you can buy an OpenWRT router for ~$12 with two ethernet ports and a case it's not obvious that this is worth it.
If we're ok with just one ethernet port then we could buy a bunch of $1.75 USB ethernet adapters. Assume $1 for a dollar store plastic case and we then have usable mesh routers for $8 a pop.