In my simple mind, the outside of the forks are all pretty much the same and all they're changing is the internal bits - springs, oil and changing the valving.
MTC do some stuff, Maxton also seem to offer a new cartridge and springs for most, I have read from somewhere that the Andreani kits were supposed to be good (but I can't find that thread / website anymore) and others are presumably available - I've spent some considerable time looking into this and to be honest, I still don't know what I'm going to do...
As for the rear, I was looking at second hand ST4s ohlins shocks and the like but people were asking £400 for them, and then they'd need servicing so it would end up costing more (and I'd have to find somewhere to put the remote reservoirs), so Nitron it will be.