Comment by LKM on http://www.codinghorror.com/blog/archives/001201.html:
Pirated media is not free to the pirate. He pays with his time. Now you can't compete with the price of time for people who don't work. To most teenagers, time is way less valuable than money. No matter how convenient you make buying your stuff, these people won't give you their money. However, that is not the case for people who have jobs. To people like us, even finding a working torrent file may not be worth the hassle if we can instead open the Amazon MP3 store, type the name of the song we want and click "buy".
In many cases, the price doesn't even enter the equation. To me, whether I have ten bucks more or less on my credit card statement at the end of the month simply doesn't matter at all. What matters is whether I spend ten minutes looking for a song, or ten seconds.
Ironically, DRM makes it *less* convenient to buy, thus giving potential customers more incentive to pirate.
About instant gratification:
If possible, allow users to download whatever you're selling. Don't make them wait for the Amazon package to arrive if you can avoid it. Give them a file they can download right after clicking "buy", and don't make them pay additionally for the privilege.