Coast was founded by a former Cal Spas exec. who apparently was not supposed to enter into competition in the spa market after leaving Cal. To avoid any legal ramifications, my understanding is that he started the business in Canada.
The dealer who I purchased my Cal Spa from is now selling Coast. Quite honestly I don't see a big difference between a Cal and a Coast. They are very similar in construction.
There is a Coast dealer very close to my office and everytime I drive by, it's either closed or there are no customers.
As with most tubs, the spa is only as good as the dealer who will stand behind it. I have heard similar issues with Coast as with Cal Spas with respect to obtaining warranty service. So, my advice is to proceed with extreme caution and make sure you clearly undrestand the terms of any warranties offered.