My biggest concern with buying anything from any box store would be the quality of the 'service'.
I am sure Costco/ Home Depot do not employ spa service people.
In my experience, it is hard enough to find service in one of their stores.
Imagine this:
• Your spa is shut off. You don't know why. Outside temp is below 32˚F. (The temp where water freezes for you southerners)
• You can't get in contact with the Costco/ HD spa-trained "customer service specialist" as he is (on holidays, in the bathroom, helping someone else, talking to god, abducted by aliens)
• They offer you the magic 1-800 number to call. (Presumably going to the spa manufacturer as Costco/ HD quite possibly just washed their hands of the repair responsibility.)
• You call the 1-800 number and get a 'repair ticket' number. The operator in Kalamazoo tells you a repair man will be out soon. They don't know when - just soon.
(Behind the scenes, the 1-800 guy is frantically tring to find a local repair guy who is willing to accept their measly $40 per hour to fix the spa.)
(Oh ya, and you live 45 minutes outside of the city. This only adds to the problem as every repair guy the 1-800 people talk to says, "NO, its out of my service area.")
• All of the service people that are willing to repair your spa are booked up for about a week with their other $60/hr jobs.
• The 1-800 guy gives you an 'approximate' repair date of "a week from next Thursday".
• YOU GO HOME AND CRY BECAUSE YOUR SPA IS FREEZING. (AND WHAT DOES WATER DO WHEN IT FREEZES - IT EXPANDS) YOUR HOSES AND PUMPS ARE NOW CRACKING/CRACKED.
"This is all under warranty", you say, "I don't have to worry. They will fix it."
• YOU FIND OUT FREEZING IS ONE OF THE ITEMS NOT COVERED IN THE WARRANTY.
• After paying your rather large credit card bill for the repairs not covered under warranty, you dream of the day when you will buy your second spa. A beautiful model from your local dealer who, by the way, has a serviceman on the payroll just waiting to help you out if you have the slightest problem.
Disclaimer: I made this story up from mixed memories of my actual experiences/ imaginations to make you think before you purchase.