I expect this deal to be freezing...
I've seen that some people have been on the lookout for this disc by itself as they have bought the sequel already, but this one seems to be a bit more hard to find, which is why I'm posting it.
It lets you add it to your basket, but doesn't say anything about stock levels. I know DVDi aren't an incredibly popular retailer either, but could be worth a punt for someone! 99p postal insurance is automatically added, but just uncheck the box to get rid of it.
Next cheapest appears to be £13.49 at DVD.co.uk.
Click that cold, go on!