I wouldn't go as far as to say that Akuma's breaking is due to user error. Go buy a Pitster Pro and an Akuma Assassin, service them both regularly, take them to a track and see which one snaps in half first.
They're just cheap bikes bud, plain and simple. I wouldn't say you'd get anywhere close to £200 for the frame with V5, people may pay that for a CRF70 road reg'd frame, but not an Akuma tinfoil frame. Sorry if it bursts your bubble to say it, but you'll be lucky to get £300 for it on Gumtree/eBay from someone who doesn't know bikes, and on here where most of the guys are experienced in pretty much all sorts of pit bikes, you'll be lucky to give it away.
And the argument you made about the bike being worth a lot because it's a 63 plate doesn't really work. I can buy a 63 plate Korean shitty car for £4000, but that doesn't mean it's worth the same as a 63 plate Merc