Here's a good example of one: Amazon.com: The Arrangement (Volume 1)...
This one has been popular for quite a while, and, just based on some simple napkin math, is pretty easily clearing over $1,000,000 this year in royalty payments to the author.
Readers seem to be split on the issue, on the one hand, they clearly hate having the story broken up this way, as a lengthy series can run well over $25. Then, you have readers who rave about the story and buy, buy, buy.
What does WaFo authors think of the trend? Good for business or a good way to piss off a fan base?