I ordered a PCV valve from advance and forgot to pick it up for over a month... just got it from them today with no trouble. I was impressed they kept it.
I find, when dealing with chain parts stores, look online first, figure out what you need, and what they have, and what others charge for it. Then you can go in, tell them exactly what you want, and that their out of stock and need to order it, and bam, you get your parts tomorrow.
I never have any trouble, just got a power steering line for the ole daytona ordered up today without incident. The guy at the register didn't know a power steering pump from a fuel pump, but it didn't matter, I pointed to the screen and he got it on the way.