Your first hot and first overhaul is generally the cheapest. At the second overhaul, the costs go up. Things that were reusable on the first, are just tossed in the trash. Anyway, our B200 overhauls usually costed $250,000-$300,000. 250 for the first, close to 300 for the second. Hots usually run between 40K-70K. Get your bird to a good service center that knows King Airs, and work with them to get the engines to a reputable overhaul facility like P&W, Standard aero, or Dallas Airmotive. Beware that there are a lot of looney tunes out there for overhauling and programs for the PT6. In pricing overhauls, you will either pay for it now, or pay for it later. If you go cheap now, something will break, and later, you'll pay for it.