If 100M is enough for you, I'm developing a new board with 2 RJ45 for industrial ethernet, which has a 40 pin connector compatible to that of RPi B+, but the circuit is adapted from beaglebone black. It's scheduled for end of January 2015.
So, $315 and ~15W max. I bet this could serve a small office well. Someone should get this down to $200 with minimal specs (and no video or audio).
It has dual Realtek NICs; it runs pfsense and openVPN well, and you can also run squid and snort if you're into it (I haven't learned how to use them yet, but I plan to).
https://docs.google.com/document/d/1X9RrbkUpiTQ-S6Acken-5fv7...