You might have damaged the keys too much so that resale value of the caps have become pretty low. Those are pretty deep scratches. Are the pictured caps the only caps with that type of scratch? Do the rest of the keys have the same scratch?
If you are unsure about the prices, you can try to drop them $5 every few days until you get a buyer. (or $1 each day, this way you might get more exposure to potential buyers since the post will get bumped each day.)
I observe that white HHKB caps are more popular than black ones and I think the current price is a bit high to ME. I would be interested if the prices go down to $30, but that valuation is solely mine and it reflects my specific needs and my wealth(budget for keyboard stuff). I am pretty sure there are other buyers who would want to pay more than what I value the caps.
If the pictured caps are the only the ones with the scratch, I think the current prices may be still attractive to others.