I had that problem a month or two ago, though it actually turned out to be a good thing. I needed some horns or a headpiece to complete an avatar I was making. The tentacle horns in Dirge of the Deep were perfect for it, but there were none listed in the MP. I kept checking every now and then, but when one would be listed, it'd be out of my price range and then quickly snatched up. I got sick of waiting for a listing, and ended up finding a new, cheaper item combination that looked even better.
And then after I'd bought the alternative and completed my outfit, about five Dirge of the Deeps were listed at a reasonable price. classified_fu