Do you think I got screwed, or is it just part of the hobby?

I agree with most, good reputable shop stands behind the work. Yhe fact that they told you to keep driving it knowing it was consuming oil is a signal from them they are guessing and maybe do not care. A reputable good machinist would want to see it to figure out what is wrong.or mistake that was made. Brand makes no difference, they use specs from each to to the work. If they fail you I hope you had it in writing or you are in trouble. If they fail you find a better shop and chalk it up as a learning experience. I have had similar mistakes with people and friends have also we now know who to use in our area, talk to others get some opinions before spending money, ask for references if they are goos should have many happy customers! JMO