eric, it's still £322 but you might be able to buy mine at a cheaper price if you want.
after some research i have found a way to get my own manufactured using stainless steel for the bed bars...
a local company quoted about 50" to get the steel milled to the 14.25mm on the inside edge and i have envisaged a 1000mm extension for about £300 rather than a mere 460mm.
if you are interested eric we could do this in tandem and possibly get it a bit cheaper between us?