I support my LBS. However, if it is a matter of saving a significant amount of money, I will buy online. I did buy a rear derailleur from the LBS for $65 when I could have gotten it online for $40. But when placing a big order, I'd rather buy online where I can save over $100.
I don't mind spending the extra few bucks at the LBS, but they are not a charity. I'm not going to just throw money at them.