Micky,
I bid and won a Therabite(new)on Ebay last fall at $201...someone really wanted it and ran up the bids but I knew what retail was so half price was better than full and insurance would not cover it very well. As it turned out, hubby didn't need it but how were we to know??
So, I would keep trying, or even better, donate it and take the deduction (I see you are a Brit so don't know if this applies.)
I am hanging on to ours for a bit but if Bill continues to be OK bitewise, I will eventually donate it..maybe even here if someone needs it.
Deb