The rules (not the whole box, just the rulebook, reference charts, deckplans and maps) are
for sale as PDF via RPGNow.
I have fond memories of
Sky Galleons; a cousin owned it and we spent whole weekends cruising the skies of Mars. You could break the ship construction rules quite easily; we built some insane monster ships! The simple campaign system was neat, with the strategic map and such.
I'll have to wishlist the Sky Galleons PDF and pick it up sometime now that I'm thinking about it!