It is dear (well not compared to some of their exhausts for gta's etc) but its n/a so what do you expect, you can't just whack the boost up and increase the fuelling.
You could of course just blow £800 at the wizards of nos for a decent setup and be done with it, but wheres the fun in that
Standalone isn't hard to find. DTA is pretty well stocked and Megasquirt you should be able to get easily enough...though you'd have to map that yourself.
Over Norfolk area Emerald stuff is attainable.
DTA is probably the easiest for you to get.