Brew - I don't call buying a spa through Home Depot a 'local purchase,' and here's why:
The bigbox stores handle tubs through a national or regional program. As such, they simply open a truck one day and its full of spas. They have a place assigned to display the tubs, and somebody usually comes in to see to it that there are brochures and info sheets. In some cases there is a local supplier, but they may be responsible for stores over a large area, and they are only really worried about making the chain store head office people happy, not the end user.
Bottom line: nobody at the store is a spa expert, nobody can teach how to care for the tub, nobody can even show you how to properly connect it and/or start it up.
Finally - let's face it: if several folks have problems trying to get after-sale service, it certainly isn't going to hurt Home Depot. But if I or another local dealer starts getting a reputation for not taking care of problems, we lose everything.