I know it's only 59p cheaper than Amazon and Play, but it's still a saving, and the cheapest I could find at the moment.
Excellent reviews on amazon. Note this is the faster 200Mbps version, not the 85Mbps one.
TP-Link's powerline adapter TL-PA211 takes advantage of your homes existing electric wires to transfer data while transferring traditional power. That means, with no additional wiring required, users can simply plug the TL-PA211 into existing power sockets and establish networking infrastructure in a flash. With high speed data transfer rates, you can enjoy video streaming, online gaming, VoIP or any other high bandwidth intensive tasks all at the same time.
Product Description: TP-Link TL-PA211KIT AV200 Mini Powerline Starter Kit - bridge - plug-in module
Packaged Quantity: 2 (specifications are for single item)
Device Type: Bridge
Enclosure Type: Plug-in module
Data Link Protocol: Ethernet, Fast Ethernet, HomePlug AV (HPAV)
Data Transfer Rate: 200 Mbps
Network / Transport Protocol: TCP/IP
Features: Quality of Service (QoS)
Compliant Standards: IEEE 802.3, IEEE 802.3u, HomePlug AV
Dimensions (WxDxH): 5.6 cm x 9.3 cm x 3 cm
Weight: 125 g
System Requirements: Apple MacOS, Linux, Microsoft Windows 2000, Microsoft Windows XP, Microsoft Windows Server 2003, Microsoft Windows 7, Microsoft Windows Vista