I have a used Spa in a Box hot tub for sale. Recently had the pump replaced, but the heating element, or pressure switch has also gone out. From what I've read online it's the pressure switch. Here's an article of how to with links to fix it, and to buy the part on Ebay. /spacyclopedia/spa-troubleshooting.htm The part cost $30.00 on Ebay : Here's what to search for there... Spa2Go-STG-SNAB-Spa-n-a-box-CLP-Comfortline-Pressure-SW
So if your handy with fixing things, this would be a cheap hot tub altogether for under $200. But if it is the heating element, the Spa in the box company tries to sell the whole power pack. The way we got around this, was we had a friend with a business licenses contact them, and was able to get the pump we replaced whole sale. Don