Sobe
What do have in mind?
I have seen a few dealers with used tubs. I suspect that these were trade in's but I didn't ask for details.
This is the Master spa dealer across the street from my office. They always have newspaper adds offering to take trades. My Sundance dealer does not accept trade in's or sell used tubs. But they are a large furniture retailer.
With other consumer goods I've checked, the dealers often pay about half of what they intent to sell something for. Not sure at all if that would apply to spas or not.