Hello, Denis ()! While I don't personally have experience finding used/inexpensive medical devices (like the cold therapy for the knee you mention), I hope that some of our community members here can chime in with their success. I do know that some people might try looking on a local Facebook group, whether it's a community group, buy/sell group, or something similar. You might have already done this because your surgery coming up, but I wonder if checking with insurance to see if something like this would be covered is an option for you. My other thought is a medical supply store to see if they sell any gentle used for a discounted price. Sorry I couldn't be more specifically helpful, but hopefully some of our community members can also share with you! I hope that you're surgery goes well, and, if you're comfortable, please keep us updated on how it goes. Wishing you a gentle day! -- Warmly, Christine (Team Member)