jesse
Touchdown! Greaser!
I'm not sure what you are suggesting.
You'd get a check, C/C number, or cash from me when I pay the bill anyway. The bill should contain the price of your labor, parts, and a reasonable margin for profit and overhead.
If I were Tom I would do exactly what he is suggesting. Why float the cost of expensive parts and risk the owner never pays you a damn thing. Much better to make the owner pay for the parts when they're ordered.
A larger shop? Sure. They can afford the risk and float and it's more efficient and easier for them to just order them.
An independent guy? Doesn't make much sense...plus complicates things from a sales tax perspective pretty heavily depending on your state.