I've never seen one either, and apparently neither had Aaron Krumhansl since he didn't mention it in the bibliography. I seem to remember hearing somewhere that Houle bought up quite a few Bukowski items when the Baroque Books inventory was auctioned off. Possible that Bukowski (or maybe Red) tipped the painting in at a later date.
I agree with Bill that Red (or somebody!) probably made this edition on his own. I do not doubt the authenticity of the painting but I'm wondering about the ramifications of other people creating limited editions well after the original publication date. Clearly, this was not the intent of the publisher. Is this a literary mash-up? This is no different than Bukowski inserting manuscript pages into his chapbooks several years after they were published and creating special "author editions" (see: Dating Undated Manuscripts thread). Do these manufactured special editions belong in the bibliography? It's a slippery slope!
I think it's pretty clear that, if Red put this together, it does not belong in the bibliography (except maybe as a footnote). The thing is, pretty much anything like this that Red did he did with Bukowski's blessing. I have a reprint of "Twenty Tanks..." that Red made (apparently a photocopy) in an edition of 25, all of which were signed and numbered by Bukowski. While I don't think this item belongs in the bibliography (except, again, as a footnote), I do think that it's a legitimate piece, as opposed to something some fanboy put together with no permission to do so.