If you have nice gear, you might want to consider giving this guy a wide berth. Doesn't seem like he is looking for an old backpack for a simple hike and I don't believe his intentions are as stated, as you can see from all the old Gregory and Chouinard backpacks/daypacks he is selling on Ebay.
http://cgi.ebay.com/VINTAGE-GREGORY-BACKPACK-DAYPACK-BACK-PACK-HIKING-MINT_W0QQitemZ220356405245QQcmdZViewItemQQptZOutdoor_Backpacks?hash=item220356405245&_trksid=p3911.c0.m14&_trkparms=66%3A4%7C65%3A7%7C39%3A1%7C240%3A1318
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320334374237
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220344548418
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220335574386
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220328333759
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220323550559
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320322466424
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320322650731
.....Climber looking out for other climbers.....