Local bike shops have been unable to compete with efficient online sellers for decades. About 10 years ago they came up with the MAP to slow down efficiencies in the market. MAP stands for minimum advertised price. Dealer agreements for all bikes and parts had MAP embedded into them. Therefore online sellers could not advertise products for under the MAP. For example Answer/Manitou forks would not allow resellers to advertise for under MAP. They went so far as to cut off distributors from selling product to retailers that did not sign a MAP. This is price fixing, it is illegal, and it has been a foundational pillar of the bicycle industry for over a decade.
The claim of support your local bike shop is hog wash, these shops are finding ways to manipulate markets to take your hard earned money. They have been trying to game the system for over a decade. I would encourage you to support them if you need their help. Otherwise buy online, and get mobile mechanics to install parts at your home.