> Furthermore I don’t want to risk some rogue employee’s goons taking it to the next level by physically attacking me and robbing me on the way to my car.
I don't think this is the right mindset—theft from your own employer is a white-collar crime. The type of people who would even be morally okay with stealing iMacs out of people's hands wouldn't be bothering to work for the store in the first place; they'd be bribing security to get in and then shuttling boxes into a van. Or holding up a delivery truck full of iMacs.
Also, getting a job specifically to steal from your employer is a pretty long-term strategy; it doesn't pay off if you only do it a couple of times. If you're doing this, you're probably doing it because you have a specific play that allows you to do it over and over without increasing the compound probability of getting caught—i.e. one that doesn't really generate any evidence personally implicating you (like the testimony of hired goons when later caught by the police), only equivocal evidence (like the fact that the person who came in to buy an iMac is a friend of the employee.) Really, generating negative utility for any individual (rather than just a corporation) in your theft, is a pretty surefire way to have someone (e.g. that same individual) take a look into what's going on.