I spotted some autographed items for sale (not on ebay!): promo cassette 'Pearl Jam an introduction' and Ten USA (think longbox, cover only, no cd). I sent the seller an email to check validity of the autographs and it sounds legit. He interviewed them back in 1992. A quick search on the internet seems to confirm this. No guarantee from me of course!
If I understand the rules correctly, I can't post the link here, so if anyone is interested, please send pm and I'll try to help out. The starting bid is too high for me ... at least for now it is. The symptoms of this collecting 'disease' seem to be getting worse!