suggestion...
forum link for comic conversion
https://www.mobileread.com/forums/showthread.php?t=11123
do a search of this forum for your topic and conversion to a LRF format file.
Searching the net for ebook vendors (use keywords)
If you can find a file in the pdf format (without DRM - digital rights management) -- it can easily be converted with pdflrfwin for use on your reader. Note: Adobe READER files HAVE DRM while Adobe Acrobat Reader files in the pdf format (do not?)
internet search for "comic ebooks"