Pricing can depend on where you live, and what model you are looking at. The best thing to do is shop around some, and then go back to the Arctic dealer and compare prices and ask them flat out for their best price on the model you are looking at.
The Onzen system has improved a bunch of the last few years. They are still not perfect though, as really no salt system is imo. We don't sell a lot of them, but the ones that we have, they have worked pretty well. Count on replacing the salt cell every year or every couple of years at most. The Arctic Onzen cell is far less expensive to replace then the Ace salt cell system.
I recommend to most to use the Nature 2 chemical system with granular chlorine, and MPS. It is very easy to maintain clear water, without using very much chlorine. If you do get a Arctic Spa, you can always try the spa out without the Onzen system, and easily add it later down the road if you decide you want to try it. Good luck in your search for the perfect spa!