Everyone's been complaining ('The Logic 7 Shaft') but I've just found an upgrade from LE6 or Big Box to LE7 for £70 at this reputable UK site:
http://www.turnkey.co.uk/tkweb/stockdetail...7UG&context=WEB
There's also an upgrade for Pro users for £200:
http://www.turnkey.co.uk/tkweb/stockdetail...7UG&context=WEB