This is actually going to be a bad thing. Many Targets are staffed by nerds like us, maybe only one or two, and they use their employee discount to buy entire stocks of these on the cheap, and then resell them on Ebay or other websites.
It's what my Target never has MTG stuff in stock, the manager buys it all and resells it.
Really? Do you have proof of this, or just conjecture?
IME, the discount from working at stores like Target is relatively low. Like 10-15% (I even know some grocery stores have no employee discount at all). Also, there are costs associated with selling online (shipping, more competition for low prices, maintaining an online store), and the time required is significant. Combining these facts, there is a pretty slim margin to be made by pulling this off. Plus, you could get fired for it.