has found a used part or excellent deal somewhere...and he's a usual good paying client, then it's a reward you're offering for their loyalty.
However, if a client is continuously bringing in parts...to save their $1/L of oil, for example, then you are behooved (word of the day, biatches) to determine a way to round out your profits, by, say taking 10 extra minutes to "cork" their oil.
The shop I go to - b/c we do alot of business with him - will tell me to get my own parts when he knows that he can't get them for any cheaper and he can't be bothered to source that part to make $20 on it. So, win-win. (He makes his real money on P-Cars, so I guess I'm his charity case.)
Bryan, increase those rates already. $70 is too cheap. Bruno will pay, Visti will pay and 95% of the other guys will pay. $75 or $80 is still cheap compared to the dealership and even cheaper if you factor in the care you provide. When your a) hydro bill goes up b) heating goes up c) rent goes up, you have to pass it on...reasonably.

Photo by Eshel "Broken Toe Cazzo Lungo" Zweig
AW Canada PW 2007