For what its worth, I look to my LDS when the item in question is one where the dive shop can bring something to the table to justify the extra expense. That can include the product's immediate availability, their expertise or my desire to compare competing models in the store. I am willing to pay somewhat more for these services. Of course, more is relative. I'll pay a few bucks more for gloves when I want them right away.
I buy online when I want a particular product that doesn't require much personal investigation or when the price differential is significant. For example, I recently order two HP steel 120's. The LDS could not guarantee delivery before March, 2002 because they are out of stock on the East Coast. In addition, the cost differential, after shipping, was approximately $300.00. Needless to say, I bought online.