It is really impossible to answer this question, because it will vary from locale to locale. Most tub makers pay less than standard wages to their dealers to do warranty repair, and the dealer also gives up the profit from the sale of the parts involved. They do so willingly, in exchange for the perqs of being a dealer, and the support the factory can provide in cases of "Customer Service," meaning those times when somebody needs to pony up and pay for a new spa or other large expense.
If you want to buy a spa without a dealer, hope that it never breaks. In fact, without a dealer, even a small problem can become a big problem in a hurry.
If you simply do not have any dealers nearby, yes, you can have the tub repaired by a local tech, but count on paying for some of that out of your pocket.
HTH