I try to factor in shipping. So for example a single Lee DC mold is $18 but has $6.50 shipping. Gun show vendor has same mold for about the same amount if you add on shipping or even a touch less. A pound or two of a different powder I want to try? Hello! Hazmat. So local source wins even if it is a couple bucks more per pound.
Where the local source loses a good deal of cash to online is in the larger purchases. If I need three molds it's still about $6.50 shipping, so I'm saving a good chunk, or my infrequent larger purchase of powder or some new shiny piece of equipment for the bench where high volume sales and an internet of competition translate to lower prices. The LGS is probably a failing business model but thanks to sites such as this we can share information one what online suppliers are good and which are less good, and which are awful. cough * CTD * cough.... cough * Bass Pro * choke!