Come join: [URL]http://steamcommunity.com/groups/ukrm[/URL]
Steam is generally ok, but right now you can get L4D from Amazon or Play for 26.99 inc p&p, compared to $49.99 from Steam which works out around £35 on your card. Sometimes it's cheaper to buy through Steam, sometimes it's cheaper with a special offer through Amazon/Play/ Tesco/Asda/etc. If you buy the "offline" media it still registers in Steam, so always hunt for the best price.
Agreed, that's why I always buy from play.com Mind you, Steam occasionally have decent deals. When the games are more than a year old, mind.