In reply to jugforathug: I'm very surprised that no-one has mentioned Wild Country Zero Cams. In terms of value for money they are easily the best and are available for as little as £33 each.
Their performance is excellent, they are lightweight and have a great extendable sling. Their durability is sometimes questioned, but I have had no real issues in the ten years I have used them.
I'd happily climb on Aliens (and have done so extensively) or Mastercams, but when it comes to my own money, I've gone for Zeros in sizes 3,4,5,5,6,6.