Watch the Lowest Bid When Building a Pool
You will have to find out what your model costs new - looks like they run from about $400 to 1700 depending on size. IF yours is at the lower end, might be just as cheap to replace it, with parts and labor. If not low end, then repair probably works. Typical pricing of components that might have gone out - switch $80, timer/control unit $130, heating element $100 (probably most likely to have failed) - so if only one of these went out, figuring $100-200 labor, probably cheaper to fix it. I would contact your dealer for a better idea.
BTW - here is a Saunatec instruction on maintenance on the heating element and rocks, failure to follow can shorten heating element life, if that is what went out (and probably the simplest to replace) -