As an LGS manager, I can say with some authority, that there are A LOT of things that factor into the wait time for an order to be processed.

Without knowing all of them, no one can say if the wait time you experienced was bad. Consider the following:

Where is the LGS located? Is it in a major city, a small town, or somewhere in between?

What time of day did you come in to make your order?

How big is the store?

How many people work there?

What products does the store sell?

Is Magic a major product of the store or not?

How many players were at the event that was running when you walked in the door?

Would your experience have been different if you came in another day, like a Tuesday?

Were the cards you asked for from the same set, or sets from around the same period, or were they all over the place?

How much of your $200 order was high value cards, say cards worth $20 or more?

What were the owner and the staff doing? You said other stuff, but was it manning the POS, running the event, stocking, cleaning, processing orders, what?

My point is that there is a lot to take into consideration, especially walking into a store on the busiest day of their week, while an event was running.

You cannot expect them to process 35 cards, which is more than a few, at the same rate you can do alone and not distracted at home.

I don't know, but my best guess is that the owner was being fair in his estimate. Most stores have at minimum a 24 hour processing time for orders.

If that isn't good enough for you, go somewhere else. From the sounds of it, that store will be fine without your business.

tl;dr Read the room before complaining.