Hmmmm, I have over 200 cds, 40 vinyls, 40 shirts and a dozen music dvds. Also some other "weird" stuff like a belgian special beer glass from the locker room of Slayer at the Fortarock Festival. Don't know who drank out of it though.
My most valuable item... Hmmmm... I guess it's my collection with all my tickets to festivals, VIP passes and wristbands.