I don't list gear for nearly new prices, but sometimes it will be closer to new than to the 70% you're willing to pay.
Lots of factors come into play, such as stock levels of new items (i.e. If out of stock everywhere then my item may be the only option for someone), market rate for the item used (which may be higher than new for vintage gear), demand (these are interconnected), condition and last but not least, how much I want or need to sell something.
If I'm not in a hurry for the money or don't need the space, then I'm happy for it to sit on ebay for as long as it takes until somebody wants it more than I do for a price that we're both happy with.