It looks like HMV is the only website selling this at the moment, everywhere else have removed it from their listings, which basically means it is going out of print. I know it says 'back in stock in 7 days' but whenever I've ordered from HMV when it says that, I've never had a problem.
I checked Amazon Marketplace and eBay and people are selling USED copies for £40-£50! Buying a NEW copy for £14 seems like a good investment!
This happens a lot with box sets, the Halloween box set for example sells for around £100 these days.