I have been using Armani code recently, it seems to be a nice subtle smell, popular for a reason I think. The other one I have used is called Allure, it's pretty good too, if not a bit stronger.
I use them mostly when going out or seeing a girl. Should probably apply it in more circumstances.
I wouldn't say though that more expensive is better, that's for sure. I tested alot of 'expensive' colognes that were meh, too-powerful, weird, or just bad. "Here, pay 90 bucks for a horrible cologne!" No way.