[Mr70]

Digital format hasn't been as profitable as many expected.The original catalogs in their original form,still with their original hardcover binder,will always be sought after.Especially to restorers & collectors who want the experience of the paper answer & diagrams at their finger tips.The ending year of the complete catalogs,as well as their revision date is key.A 1955 to 1980 catalog will lean towards the later revised 1980ish part#'s,then a 1955 to 1970 catalog will.And a guy restoring a 1970 Camaro to assembly line status will see as less attractive & avoid.Most of the digital formats are copied from the former..
Depending on condition,I've seen them sell for $350-$550 swiftly w/many indoor & outdoor swapmeet vendors,where they seem to be greatly desired.