Bought a SRAM Rival 10 speed 11-28 cassette from my LBS. It's a brand new product so only available through the distributor. Can't find it at Performance or Nashbar, etc. The part costs $99.99. My LBS installs it, adjusts the FD, RD, brakes, etc for me to make sure nothing is rubbing and shifting smoothly. The whole job took about an hour but they entertained my questions so it took a little longer. The total came up to $122.36.
That is freaking cheap. If I had brought my car in to a shop, bought a cosmetic part and had it installed, you can bet they'd charge me an arm and a leg just for the labor, let alone the huge mark-up on the part. Yeah, I know, the LBS had marked up the cassette. Still, it's pretty cheap for a drivetrain component.
How the heck do LBS's stay in business with such a thin margin?