Possibly on Usenet. Depends if your ISP carries Usenet but if you have to subscribe to a Usenet provider you'll definitely find something like alt.binaries.comics or some other form. Lots of afficionados post pdf copies of older comics, especially those which are hard to get hold of.
Tough to come by....found two in a rental house this past Summer, brought back memories. May check Ebay. Thanks though.