I've received these for a while now.

I actually ^ INCREASE ^ my prices if they don't sell, as my items are artwork, and I see them as rarer if they don't sell, so the value goes up.

I often find that if I increase my prices, they start selling.  A have a couple of theories: buyers wanting to buy it before it goes up too high or eBay being greedy and showing my items more when they get more fees from it.