A cedar sauna kit costs meaningfully more than the same kit in hemlock or spruce, and the premium is real rather than marketing. Whether it is worth paying depends on which parts of the cabin are cedar, what grade it is, and whether the cabin lives indoors or out in the weather.
What cedar actually does
Western red cedar is dimensionally stable through heat and humidity cycling, naturally resistant to rot and insects, low density so it stays comfortable against skin, and it smells the way people expect a sauna to smell. Outdoors the rot resistance is worth real money. Indoors you are largely paying for stability, comfort and the scent.
Clear grade against knotty
Clear cedar is knot free and costs substantially more; knotty cedar has the same species properties with knots that get hotter than the board and that some people like the look of. The sensible compromise most good kits make is clear grade for benches and anything you touch, knotty or a cheaper species for upper wall areas.
Which parts are cedar
Read the kit specification carefully. Some kits are cedar throughout; others are cedar cladding on a hemlock frame, or cedar benches with hemlock walls, and all three are sold as cedar kits. The parts that matter for comfort are the benches, the backrest and the door surround, in that order.
Upkeep and the scent
Cedar's scent fades over a few years and comes back with a light sanding. Never seal the interior. Outdoors the exterior wants a finish annually or two yearly, and cedar takes one well. If anyone in the house dislikes the smell, hemlock is genuinely the better buy and cheaper, which is the one case where the premium is simply wasted.
Questions people ask about cedar sauna kit
Is cedar worth the extra?
Outdoors, usually: the rot resistance earns it. Indoors you are paying for stability, comfort and scent, which is a preference rather than a necessity.
Clear or knotty cedar?
Clear where you touch it, especially benches. Knots get hotter than the board around them. Knotty is fine on upper walls.
Does the cedar smell last?
It fades over a few years and a light sanding brings it back. Never seal the interior to try to keep it in.