Just picked up r134 machine for this years rush. My question is what do you guys charge for a evac/recharge, leak and performance check? I was thinking about billing refrigerant out by the ounce. Say I take 13oz out of a car and it calls for 18oz just charge them the 5oz it was low on. All the shops I ever worked for just billed a 1bs or 2, no matter where the system was charged to during intail inspection. I'm at 149.99 on this service. Thanks.