It's worth more than $500 to me. I bought it for more than $500. It is only worth what someone else is willing to pay for it: it must be worth more to me than others so I will happily hold on to it.
I have amassed quite a collection of Bukowski over the years; this first edition being the most valuable. I have kept it in a shadow box and it sits in my bookshelf. The time has come to part ways with it, and I would like for it to go to a good home. :-)
(I am also hesitant to go through Ebay...