I just wanted to add, that 150 dpi scans CAN be scaled up, and provide acceptable results for printing with a little work. Here's the first page of Daredevil Battles Hitler #1 from this site, that I upscaled, and was printed (in B&W) on page 46 of Alter Ego #103:
Sorry, but I missed this before.
@srca1941: May I ask you how did you edited the image? Not about the upscaling, but since you said it has been printed in Alter Ego (and thus, I suppose, in four-color): did you edit it to separate the black of the artwork lines from the color part, and then re-paired the files afterwards? Having high-resolution scans (more than 300ppi) is needed if you wish to work on an actual restoration of the original line art/black.
For example, I scanned italian newspaper-sizes comic publications of the 1930s and 1940s at 600ppi, but to have a proper rendition of the linework, if you wish to restore it, and re-pair it afterwards with the other color plates, you’d need to scan at 1600ppi (or even more). I am still studying the thing, but 600ppi was a forced choice, since the Canon color copier I used had that as a maximum resolution.
This explains also the nature of the question I posed to rangerhouse: as qualitatively high as they may be, generally book scanners does not seem to go beyond 600ppi. That’s why I thought mostly of flatbed scanners.
