As best I can tell, the Sunless Sea poster-size version of "Demeaux’s Navigational Chart of the Known Unterzee" was available for the Kickstarter, enjoyed a (public) second print run a few months after the official release, and there was never a third print-run. (So only second-hand at the moment, and a quick search, after sifting out Anne Perry’s okay novel, yields no positive result)
The Sunless Skies Sky Charts from the Kickstarter were only released 2 months ago, so even getting one second-hand would be tricky at the moment. For exclusivity’s sake, any hypothetical public print run wouldn’t be for a while, although optimistically it might be within the year.
Optimistically, any future print-run would also offer the Sunless Sea map again, and maybe also a Fallen London map? I haven’t seen any official mock-up for a hypothetical Fallen London map, although we do have the unusually detailed Travel map as a jumping-off point.
