If a smith charges $500 to build/chamber/thread/etc... a rifle. And he builds 1 rifle during each standard 8 hour business day (which is completely possible). That's $2,500 a week. Which in-turn (x4.33) becomes $10,825 a month. Which adds up to $129,900 a year. This is all before taxes, but still, that's a pretty good living just for building 1 rifle a day. That's not including if he does more work, or more than 1 rifle, or starts another build, and is averaging 1.5 to 2 rifles a day in just machining labor.
That being said, those guys that are charging you $2,500 in labor to build your rifle, think how rich they are? If they build 1 rifle per day at that labor price, you're looking at about $650,000 a year.