The main issue you'll run into buying an Aria is a Hot Spring dealer must perform warranty service on the spas they sell. So, if you're in Oregon and you buy from someone in Florida, the Florida dealer must provide the warranty service. That keeps the dealer base from selling on the internet and selling out of their area.
However, in a situation where you don't have a close dealer, that is relaxed a bit. I'll bet you'll have a dealer within a reasonable distance. If you can't find a dealer on the dealer locator, do as Spatech said and call Watkins to find the closest dealers.