This is a nifty device which can be used in a variety of ways, to share a single network port to provide a local wifi or cabled network, or, to share a wifi link with a local cabled network.
Full details here: http://uk.tp-link.com/products/details/cat-9_TL-WR810N.html
I've never seen them below £20 before.
They can also be reflashed with openwrt and gain vpn functionality and other advanced features. Because it's got a USB port, you can then connect a 3G dongle.
Disclaimer: getting that wrong could permanently brick your router!https://wiki.openwrt.org/toh/tp-link/tl-wr810n