D-Link DHP-307AV/B 200 MBPS PowerLine 2 x Homeplugs
Yes, there are cheaper ones at eBuyer, yes these are not passthrough.
But they do have:
2 year warranty, a very high percentage of positive reviews and hardly any bad reviews, a smaller block profile than the eBuyer ones, and are eco-green.
To my knowledge this is the cheapest the Dlink ones have been.
Free super saver delivery + don't forget Nectar points.