Stent cost will depend on number of stents involved (if stent is required -which you will not know until angiography, if indicated, is perfromed). In a government hospital, the main cost is for the stent device itself.
BTW Banglamung is a government hospital and hardly "fancy-schmancy". Also probably does not do stents as it is just a district hospital.
Sirikit Heart Center is very good. I doubt it would cost more than care under Medicare taking onto account air fare etc.