Roll centre are quite expensive for what they are! More expensive then a mega-spec Safety Devices badboy.

The SD challenge spec cage is a bit much for me I think, don't fancy my chances of being able to fit it. Apparently its a pile of straights and bends weld it together yourself kinda job, although it does look awesome!

Someone on the 205 website does custom ones from £200 which could be a plan (don't need anything too fancy its just a cheap track shed )