Hey, just spoke to the guy properly, here's the deal:
He can do one-off's (so your car is more unique), but group buys are much cheaper. His work is massively labour intensive as he uses the F1-style Prepreg method to forge the fibre, so once they make a mould it's easier to roll out loads.
In terms of performance, having a carbon bonnet, for example, will weigh 4-5kg's instead of 25-30kg's. You start from the bonnet and work your way around the car, and you can chop off a few 100kg's !
In terms of cosmetics, the weave is perfect (see the pics), and unpainted does look good, and the guy can make little things like wing mirror covers.
Prices are around £800 for bonnets, £150 for spoilers/skirting, £80 for wing mirror covers, etc (these are just guideline prices). Obviously these are low quantity prices, which is why the guy is interested in group buys, the more the cheaper!!
Here's a few pictures
Cheers!