There's certainly something to be said for thriftiness, but there's also a matter of professionalism to consider. LearLove, what sort of impression do you think it'd make if you showed for a flight with your flight kit contained in one of those paper grocery bags with handles? I'm sure you could fit all your stuff in one, and it's far cheaper than a flight case from Scott Leather, right? For that matter, why bother with a headset? Every plane has an overhead speaker and a hand mike, and you can just use earplugs--or cheaper yet, just stuff cotton in your ears, right?
Obviously I'm taking things to the level of hyperbole, but especially in this market, CFIs have to sell an image of professionalism if they want to make the impression that they're going to provide professional flight instruction. How they dress, how they conduct themselves, and yes, the tools they choose to equip themselves with, all speak to that image of professionalism. Showing up with your headset in a Tupperware container sends one of two messages: a) you're slightly nutty and thus, your judgment is a bit questionable, or b), you cut corners wherever possible and thus, your judgment is a bit questionable. Either way, you're giving someone a reason to not fly with you. As I suggested before, in a market where CFIs are a dime a dozen, giving people ANY reason to fly with someone else is simply stupid. It's the same reason you went and bought a conservative navy blue suit for your airline interview.
Beyond the looks thing, I marveled at your suggestion that people just go with a passive headset. Either you don't understand the long-term damage to your hearing that can be prevented by using an ANR headset, or your hearing is worth less to you than the $300 difference in price. Being from the generation who spent far too many hours with their walkman volume cranked to 10, and suffering a not insignificant amount of mid-range loss here in my mid-30's because of it, an ANR headset was a no-brainer. Having made that investment, the second no-brainer was to buy a padded camcorder bag to protect it from the school of hard knocks, which delicate electronics don't respond to well. I bought that bag at a consumer electronics discounter and guess what--I paid a 25% premium over the price of the Sky High bag above, for a bag that offers less utility in terms of organization and storage. In other words, I got less value out of my bag than the Sky High one offers. Even the thriftiest shoppers know to shop for best value, not lowest price.