Right now, this is half price at £15 in Boots. However, whenever you spend more than £10 in store, you also get a voucher for £5 off fragrances.
I didn't know this until I'd bought the aftershave. I then bought another bottle and used my voucher. Then I returned the original bottle I'd bought. Took about 2 minutes in total and you get a pretty decent aftershave for only 10 quid! :-)
Edit: To get the £5 voucher, you only need to spend £10 in store in anything.