Mizuno, I make the same argument - I don't clubmake to make money (yet).
I try to explain that grips are cheap - just regrip with brand new grips.
The first time it happened, I had nothing in stock that the guy liked, so we just turned his grips (for free). Now, he comes 3 times a season, and has his grips rotated 120º (about a 1/3 turn, wear to the lead palm).
Then he told a couple guys, and I figured I had to charge SOMETHING... and I actually thought 50% of my grip cost would be a bit of a deterrent... but these guys are the kind of guys that want a discount if they don't wear spikes and promise to sweep the ball...
This is NOT an 'adverstised practice'.