That said, I love reading comics and I use Comixology heavily. I just usually wait until I can get about 50 issues of a title in one of their 99 cent sales and splurge for a good month's worth of reading.
I agree with getting huge chunks of a series though. But that doesn't always work since Marvel and DC are still big on story arcs that cross over several titles. Following a single title often leads to incomplete stories.
The comic book store I used to go too closed down a few years ago. I'm sad to see it go, but the industry is going to have to change to survive.
They were doing the sale every week, and it's always something different. I've picked up huge continuous runs of Deadpool, Daredevil, and the Walking Dead.
The way it works is that currently almost all physical Marvel issues and some hardcover collections come with a code that can be redeemed for the digital copy. People who have a physical copy often don't need the digital copy too, so /r/comiccodes/ is a marketplace where people sell those codes. The going price tends to be $1/ issue and most people take Paypal, although some prefer Comixology gifts or Amazon e-giftcards or whatever.