Actually it doesn't matter.
People will spend their money where and how it makes the most sense for them. Idealy they will factor in things like the social hub and table space a LGS offers.
But how much that is actually worth is going to vary greatly from person to person. Myself I figure table space and the rest is worth $5 per season. For some people that means there's no reason to ever buy at a LGS because they'll never play there.
For others that may mean they will buy everything from there because they play there all the time.
So buying from your LGS vs online really has to factor in just how much value someone actually gets out of a game store.
Edited by VanorDM