With used gear in an environment where new gear are having to have substantial markdowns for sales people notice. If velocity of used sales and prices have a downward trend, unless someone finds their dream piece and jumps on it, time will go by with perhaps other like equipment listed competing with your ad. People will notice that too.
So, if I see something that intrigues me enough to make an offer, I may offer a lower price, one which I feel is lower than what I would pay but I want to feel out the seller to see how much wiggle room they have. This way, If I really want the item I can at least get it at a lower price after some haggling.
If I place the ball in the seller's court and ask if they could do better, I might get a little discount but they will then know I am interested and the momentum may not be on my side.
If I see a seller is a bit more determined towards a sale, I will try to get them to move a little lower.
In my experience in buying, I usually only go after something I really want. So, if I can get it for a bit less, great. If they don;t move on price and its for me fair, I will still buy it. If as seller just flat out offers something at a lower than expected level I won't even ask if they could do a bit better, I will just buy it.
As a seller, I have sold speakers I had to come down on and still wait patiently for a sale. I believe I got the lower side of my expectations but all parties happy.
Now have listed some gear, nothing rare but good for their price points and figure I will have to wait it out and perhaps haggle a bit for a sale.
Your stuff is much more specialized. I would do the research on pricing and ease of moving a particular piece of gear, shipping. etc., to determine a reasonable expectation on both sides. Expecting nearly half of retail doesn't mean anything to me. It's what it's worth at the moment. If my expectation is too low for whatever reason, I don't list. If there's too much of a certain gear for sale, I will watch what happens first.
Then there's the economy to consider. I feel that alot of people have their attention on other matters at the moment and that can detract from one's sale. I need food before I need gear. It's Spring and people focus on moving. Perhaps looking for a higher paying job is someone's focus. Then there's relationships, marriage, life changes often occur in the Spring, so there's that to detract attention away form used gear.
And there's the fact I already have all the gear I feel I need for this hobby, why buy more?