Easily explained. He had hundreds of copies he couldn't get rid of, but 50 that he could get rid of. Those are the ones that were sold; he still has the hundreds that he cannot get rid if.
Sorry, I read that differently. I read "He has (had) hundreds of copies; the 50 he had listed sold out in 24 hrs.". Possibly he still has another 50 or so to go
Maybe Arkhan should be pimping Insanity and Pyramid Plunder here. Last I knew he had quite a few of each leftover...
<Alas, no Atlanteans until the printer gets fixed...again.>