I have often noted in the buy/sell forums people panicking if their item for sale doesnt attract interest in a few days after posting.
I always look at it this way. There are always two prices levels that an item for sale for could sell at.
First is the price that someone would pay if they were already planning to buy that item, and second is a price that someone would buy it at because its too good a bargain to pass up and so they then justify to themselves a reason for having it.
The fact is that there isnt always someone planning to buy widgetXYZ right at the time you are wanting to sell yours.
My advice is if you have patience to wait for a buyer, you can usually get a good return.
I have sold a 27mm panoptic, and an ED80. I set what I considered to be a fair price, and in both cases had to wait about a week for a firm buyer. Such expensive items often have potential buyers pondering their decisions for a while anyway. Clearance prices are another matter and of course will attract buyers quickly.
In short, dont panic !!