Is the thread holding any tension? If it’s not you can usually get threads to back out with a sharp scribe, it sometimes helps to prick punch a small bit for the scribe to grab into. If it’s holding tension you’ll have to go the drill/easy-out method, but chances are any easy-out/screw extractor will cost more than the part.
Also if it is holding tension, can you use a clamp to pinch the part and relieve tension?
I’m a fitter/machinist by trade and have to deal with this sort of thing weekly. Its usually when inserts break on cutting tools and take half the screw with them.