I have struggled for a long time with my movement trays. I know there are several articles around about making them yourselves, but my attempts have either involved something flimsy or something that warps as soon as I apply some green paint to try and match my tabletop colour.
Donnachaidh bought some at this year's Salute, and gave me the link as he was pleased with them.
I have now bought some of their plain ones which I think I can manage to base myself.
They are made from resin, so nice and solid and warp free, fit the GW bases nicely, and for those of you who have struggled to make your own, and also want to spend your hobby time on other aspects I think they are quite reasonably priced as well.http://www.terrainwarehouse.co.uk/category.aspx?CategoryID=24
The link is straight to the rectangular movement trays, but they do other stuff as well.