Hi, I came across a similar thing the other week. I was looking for a toolbox lid for the 400, and saw one on Ebay for £225
.
I emailed the seller and suggested that he had the decimal point in the wrong place - they're normally £22.50.
He told me that he had none in stock, and had jacked up the price so that he didn't "lose his listing" until he had more in. Sure enough, a week or so later another batch was in, and the price went back to £22.50.
Perhaps that's what's happening with the rubber?