i suggest everyone who's interested to fallow their facebook page as well, as they sometimes post there about discount news and such. i bought a video last week with a 25% discount or so, just like that :)
It's £15 in the UK :/ ($24 USD / 17 Euro) - discounted to £11.24. It's supposed to be 18 Euro and about 13.50 Euro with the discount? The US version should be $20 and $15 respectively. Apparently Valve set the pricing.