For military operations it might actually be a possibility to just not relaunch though. Explode the engines/anything sensitive and just leave it there. They're surprisingly cheap to build (compared to a lot of the expenses incurred during combat operations), at a (public and old) target of $5 million/ship.
I think you're probably looking at a few more million in launch costs, but those aren't recovered by recovering the ship anyways.
Though the Falcon 9 is $55 million, now that's comparable to a modern fighter jet.
Bear in mind that it is only the Starship (upper stage), not the Super Heavy booster, that would be landing at the destination and hence potentially subject to abandonment. Also note that Starship, unlike Falcon 9 (or at least to a much greater extent), is designed to be produced efficiently in quantity.