That's great and welcome for a lot of people. From reading posts in this forum people can get the so-called mover discount combined with other savings to get the cost down.
But don't know if it's accurate or even necessary to say Best Buy always or often has more inventory available. Quite a few us, myself included, have posted on this topic we were able to walk in to an Apple Store and get what we wanted.
The online experience however leaves a lot to be desired. That you can't order anything online other than the base config for store pickup is more than inconvenient. The iOS Apple Store app doesn't even have the option for any config. And calling a specific Apple Store directly isn't even that easy any more. Unless you do some gymnastics with the options presented you're routed to someone off site which is why people are also probably not getting much luck calling ahead to check that store's inventory. They're getting someone somewhere who seems to only have access to the same thing we see on the online Apple Store.