to be fair, the groupset does put the price a it higher but i'm still convinced, based on other sales i've seen here, that most people won't consider anything above 400. it'd be great for you if i was proved wrong. i would definitely be making you an offer if i was in the market for something...
money
there have been a few batavus on here in the past couple weeks for a lot less. I think you'd get luckier trying to get between £300 and £350. its a big drop from what you're asking but it seems to be the going rate.