Drug Seeker

I was at drugstore chain X today and saw that a dietary supplement I normally buy (24/$6) was on sale- the large 60 ct box was 75% off (60/$2.75).
I asked for it and was told they were out of it. I had them call the other store and overheard this conversation:
"This is (name withheld) at drugstore chain X. Do you have dietary supplement in the 60 ct box, at 75% off? ..... Female..." He turned around and glanced at me, before quickly turning back, "30's?... Okay. Thanks!"

Yes, they had it.
I drove across town and walked directly to the back of the store and requested the dietary supplement, in the 60 ct box, at 75% off. The woman I spoke to said, "I don't think we have that."
"Yes, you do. Twenty minutes ago, the pharmacist from the other store called to check."

She walked back behind the shelves and asked a co-worker, "Did someone call from the other store about dietary supplement?"
The co-worker came out from behind the shelves and looked at me.
"Yes, we have that. I need to see your ID." he said, and reached for a box, and began to ring it up.
"I'd like four boxes, please." I said pleasantly.
"I can only sell you one." he replied.
"I did not see that stated on the sale tag." I countered.
"The active ingredient in this only allows us to sell one box at a time." he explained.

I took a deep breath and unleashed my inner libertarian:
"Federal law limits the daily purchase of active ingredient to 3.6 grams. This box contains .75 grams of active ingredient. Four boxes is 3 grams, which is within the limit. This is an excellent price for a product I use, and I'd like to take advantage of it."

He stared, mouth agape.
I smiled. And waited...
After about 15 seconds, he leaned forward and said, "Come back in three days. Otherwise, um..."

Yeah, they'll flag me.
Got it.