I was looking into single board Arduino Ethernet, where the Ethernet circuitry is on one board with the ATmega, as opposed to being on a separate shield. You may find this link useful, 10 Best Ethernet Shields For Arduino.
- Arduino Ethernet w/o PoE, $59.95
- Arduino Ethernet Development Board A000068 *Brand New*, £10.72 – Same as the SparkFun, w/o POE, but way cheaper
- A000022 Arduino Arduino Ethernet 2, for £39.99 (as above but with sockets already soldered in the holes)
- W5100 Ethernet Module for Arduino With POE/Xbee/SD Slot Iboard Precise, £21.59. This really is a standalone controller, as it has a non-standard form factor, and will not accept shields.
- Arduino PoE Module Add On Bolt On, £18.26 + £1.45 (p + p)
- Or cheaper still, 1x X000010 Extension module PoE pin strips In the set prototype board, for £11.59 + £2.98 (p + p)
The Power Injectors
You will also need to inject power into the Ethernet. These seem to vary in voltage, 12V, 15V, 24V, 48V:
- The extremely dangerous looking POE Power Supply 48v 0.5A PoE Injector Adapter US Wall Plug Power over Ethernet, £3.89
- 15V 0.8A POE injector Power Over Ethernet Switch Adapter Injector Power Supply, £3.45 + £0.80 (p + p)
http://datasensinglab.com/ for Distributed Network Data