I have to agree with Mingaa on this one. The guy who works at Academy is there to do a job. If it were as simple as some guy buying from a supplier and selling to a consumer, that'd be one thing. But this is a guy who is paid to be there to sell to customers, and he's taking advantage of his position to undercut his employer, especially if he's getting a discount. And when I say it's undercutting his employer, a customer will only visit your store so long as you have product. If that product is being taken away be the store's employees, yeah the store is still making the sale to the employee. But what it's retaining in original sales, it's losing in impulse buys. The customer that walks in to buy the box of 9mm might also buy an extra magazine on the shelf if he sees it, then maybe pickup some beef jerky on the way out. Working in retail management taught me that impulse buys were very important, as that's where the big markups can happen.
While what lonestar is saying is right, this kid probably isn't an idiot, there are other aspects to look at. I guarantee you if this kid gets reported you'll be able to get your ammo at a better price, and hopefully this kid will learn a thing or two about respecting those who give him a job and not trying to "stick it to the man". And that's something we're needing these days.
EDIT: On a side note, my last trip to Wal-mart had a kid behind the gun counter bragging about how he gets first dibs on any ammo coming through, mainly .223, which is what his customer was asking about. This might be partly why there's an ammo shortage. I guarantee you there's no shortage (pun) of high-school or college-age employees doing this everywhere else.