not quite as easy....
there are not thousand of fascimile copies of the 1st salem's lots out there...
and since these early works by king were not professionally produce book covers, but simply low tech high school produced quality - they'd be much easier to photocopy and pass off than a professionally manufactured salem's lot book jacket.
i do have to admit i'm surprised at the prices that the 1st state salem's jacket commands... someone with the right equipment hasn't already tried to professionally forge some of these jackets...
this is where proof of provenance is important