Might not be the cheapest going but for £17.99 I like the look of these netgear powerline adaptors. 2 for £36 delivered is about as cheap as these things get I believe. If anyone has any tips on better types or deals please let me know. I am just looking at the alternatives for the XBOX wireless adaptor at present and this looks like a groovy option.
One thing that does look particularly appealing is that its as cheap as a decent twin pack to buy 2 of these and purchasing 3 if necessary doesn't break the bank either!