It's surprising how many reviews mention this game and how much they enjoyed it but it's not available. Perhaps something hyped and died out?
This game was released by a company that is now gone. Many other titles by the same company are difficult to get (though there's still stock out there in various places, mostly stores that don't have online storefronts, so rare items stay in stock for longer).
Actually it is worse that A Handful of Stars, which I consider masterpiece in game design of deckbuilder with a board, is completely unavailable now. It was the last title and a limited print run by that same company.
The only hope is that another publisher will reprint them, but at this day and age where 'new' matters more, it might take a while.
I think it helped that it was one of the first games to integrate deck building without making that the entirety of the game. Since then other games have come and done that, with various themes, even some by the same designer.
It also probably isn't helping that the game has a dominant strategy (some might say it's broken) which the designer says couldn't be completely fixed without deviating too far from history.
Actually the dominant strategy is 'fixed' with some tweaks, but overall it doesn't matter. It is still a great game even if you know ins and outs of that very specific strategy.