Buy quality, because it's cheaper than buying cheap multiple times.
It's hard to find information online about some Snap On tools, but these came recommended by a machinist friend as the best type of extractors for broken bolts and studs. I had a nasty one, and other easy-outs just spun and stripped, while the Snap On gripped and fought the stud but won in the end. These are expensive, but so is removing a cylinder head and taking it to a machine shop. And a real pain. Recommended.
Using these with a little bit of the blue wrench to heat up your stud after drilling it out to the proper size then hammer this into the stud slap a pipe plug socket onto the end of this extractor and break out your breaker bar or long pattern ratchet and it will get the job done and they are warranted for life far superior to left hand drill bits