Zerona 699.00 for 6 Treatments?

Hi
Likely the reason is that the spa bought the machine 2nd hand and is banking on selling twice as many at half the price. Perhaps their average price point that is attractive to their clientele is lower and so they figure that if they lower the price enough they have a better chance to get more of their clients to do it. One thing to think about is maintenance. The machines are highly calibrated, and so if the spa does not regularly service (at a cost most of the time) then the machines may not work as well. It is always best to go to a reputable place that you trust, not just the place that has the lowest price. Also, it may be introductory pricing to get you to try their spa. Perhaps this gets you in the door, and they have a new client who does other services now because you liked them and got a good deal. Lots of reasons. Trust your gut. If it seems too good to be true, it probably is. 
all my best
Dr. Jamé