Where have you tryed selling them? I would just post my books to anyone that wants them. I'm trying to get rid of a lot of stuff. My niece has made a small fortune on ebay with a few of my things, I normaly just give it away but wean needs some cash and it good for her to start making a little pocket money to show her it dont grow on trees.
o.k you should keep a look out for those boxing fayres, if there are any near were you live. You might get a bit of luck that way.
About 2000-3000 fights, loads of books that I hoard but won't read again, bits and bobs of memorobilia. No mags.
I must have 10,000+ fights on DVD, 50 or so books, every Boxing News since 1994, almost every Boxing Monthly since around 2002. I've got a few posters as well but they've been ones which fighters and trainers have given me and I've just stuck them in a corner somewhere.