There are varying levels of C check as well. For instance on a 747 prior to the MSG 1,2,3 format there were typically 6 levels of check done with the C3
being very "heavy" affairs taking up to six weeks.
At brand X checks were costing around $78 to $84 per man hour in 2002.
At a repair station where I repped an MD83 the check was billed out at $49 per manhour in 2004. ( I have to say that it took more hours than the airline but they claimed to have saved over 25% compared to the cost of doing it in house.)
Current belief by the "bean counters" is that third party is a lot cheaper than in-house. Especially when you can get the check done in China, Costa Rica, Peru, or Indonesia for around $30 an hour or better.
At those prices even the down time after the plane gets home to fix the bugs is paid for.
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533