its amazing the markup the stores use to pay silly things like employees and rent...
I make a point to buy from LFS's, it's what keeps them around. I know when I worked at them, how many folks would come in and pick your head for info for a half hour answering their questions, then tell you that your bulb was marked up $5 higher than Petco, so they were going to go buy it there. Well, that $5 is how they could afford to pay for a person who knew what they were talking about, instead of the minimum wage guy who didn't. Plus as much as I don't mind purchasing corals online, I'd hate to see the day when there weren't LFS's to go browse through, and so I don't mind picking up dry goods to help them stick around.
But I'm also one of those weirdos who doesn't buy from wal-mart because I prefer to support U.S. products, so I'm understandibly odd man out from the norm.
I do purchase many things online, but what I purchase online is things that LFS's don't carry, such as bulk supplies.