Sure. If enough folks want to dig into this much detail, I'd be happy to put together an in-depth write-up.
PayPal is still the cheapest and easiest way to collect the money, even considering fraud. (PayPal almost always sides with the buyer and with digital goods you have little recourse.)
It's the marketing that makes all the difference. We have customers that have made $50-60k in less than a week due to awesome marketing. And we have customers that pull in well over $100k/yr due to good marketing and good affiliates. We also have many that will never sell anywhere near that much in the product's lifetime, also due to marketing.
You wouldn't by any chance know of some resources related to getting over the initial hump of getting paid for software/services, would you?
HTH!
Great job with this!