I don't feel guilty when I buy online but I only do it for selection, not price. If I can get what I want locally at a store that I like to patronize, then I shop there. There is one store near me that doesn't seem very friendly unless they think I am looking at the machines they sell, then they are very friendly. I don't go there very often. But the others get my business if I can find what I want.
When I consider shopping online to save money, I remind myself that if I do so, that will soon become my only choice. Shops that just have an online presence and no bricks and mortar have an advantage in pricing. I'm not willing to save a few bucks when I consider the consequence of potentially having no LQS. But I will shop online without guilt if I can't find what I want locally.