Ethics & Morality

I can't believe I haven't written about this before, but here goes:
I usually consider myself someone with very well defined morals (and I do my best to live by them). But when my iPod reselling extravaganza was in full swing I realized that, in terms of the business world, I sometimes couldn't figure out what was right and and what was wrong (i.e. Is it right to sell something to someone at markup when they could get a better price at a public website?). I had always thought the idea of a course on ethics was ridiculous, but I now want to take one of these classes just so I can see where other people stand (and then draw my own conclusions).
And I've been questioning myself again as manager of the BFSC snack bar. From what I understand, my sole reason for employment is to turn around a foundering enterprise. But just how far can I go? It a classic question of ends, means, and justification. If I don't care about customer satisfaction and disregard the happiness of my employees I could probably generate a fortune. But how far can I push those limits and still like who I am? For now I'm going with, as in so many things, happy mediums.