I'm late with this one. Find-DVD failed to alert me to the fact that Amazon have reduced it to £4.98 (excluding shipping) and Play.com have reduced it to £4.99. It's OOS at Play.com, so it's probably been at this price for a good few days.
Even though I've been waiting for the box set, £2.50 per DVD is too hard to resist when DN is #2 on my top 5 anime list. I'll keep it sealed on my shelf until I get Vol. 2.