I sold mine for about 50% of the price I paid for it, not including shipping. I think I did pretty well. Since if I had waited, the prs-505 would have already come out and I would have had to sell mine at much lower price.
Of course, it is a bit expensive to buy a new reader every year, at least for me
, but that's the price for adopting new technology. I expect I will sell the Cybook as well in a year or two. Only when eInk will have mature enough I will consider buying for 'keep'.