M0n0wall 1.8.1 released
m0n0.ch
m0n0.ch
It's a shame this isn't portable to ARM systems, where $50-100 buys you much more than that. Buying a small, low power x86 system in quantity 1 raises the overall price significantly.
http://output.chrissnell.com/post/39550480075/the-jack-of-al...
I didn't see it in the feature list, but that doesn't mean it doesn't exist.
m0n0wall is made by the same guys that make Threema: https://threema.ch/de/