I've had this discussion with benhollberg in some other threads a few times.
If someone wants to buy something like an iPad and resell it for $5000, then whatever. Someone who really wants that iPad NOW will be an idiot and pay it. There will be more iPads later that are the exact same, for the normal cost.
It's things that have a finite number (like tickets to a concert or sporting event) that pisses me off with scalpers. Take a concert, and a scalper buys all 300 seats in the closest section, jacks up their price five times, and then resells. Your only chance to see the band live if you don't happen to get another ticket, is to pay the scalper's prices. Of course, you can just choose to not see the show (which is what I do). It's not the same as the iPad situation above, where you can just wait for more iPads.
There have been several occasions where I am online hitting "reload" waiting for tickets to a concert to come on sale. It goes straight from "tickets are not on sale yet" to "there are no more tickets available". And what do you know, that afternoon there are hundreds of tickets on ebay for 5 or 10 times face value. That's not a service. That's a scam. And those same damn tickets are still sitting there until right before the show. I'm not even looking for front row tickets (I don't like being that close), but everything is highly overpriced.
Tell yourself all you want that you are "providing a legitimate service" for "people who can't wait in line" (do people still wait in lines?). If you were providing a service, you'd offer the $50 ticket for $70, not for $500. I'm interested in people you know who have always given you positive reactions to what you do. I've never heard a positive word said about a scalper.
