Wow, lots of new places for me to check for ebooks!
I have a Kindle Keyboard, and a Kindle Fire. I have found that I prefer the Keyboard one for reading books. The matte screen has no glare, and the font controller is much better. The shiny screen on the Fire, and lit screen are harder on the eyes, especially at night, and there are limited font sizing options. I love my Fire as a tablet, though. DS had an iPad, and used the kindle app on that, and DH has used the Kindle for PC app.
I have yet to pay for a book - I generally start looking on Amazon's top 100 free list, and download anything interesting there. Many are new authors, some are junk, some are surprisingly good. Some are a short time deal, so I check often. Some are free for the first in a series. I like classics, which can also be found on Amazon for free - there are multiple versions, some are not free, but if it is out of copyright there is a free version somewhere. I've used Gutenberg, and Overdrive on my library's system website. In fact, my DD is currently based on the other side of the country, but can still use her library account to access ebooks thru Overdrive, since it is all online. I know some snowbirds who have library accounts in two states; they could use both online.
My library also has Zinio, which is a service providing emagazines for patrons. I can view them on my Kindle Fire with their app. Those are yours to keep, they never lock up like Overdrive books. There is also Freegal, for free+legal music downloads (again, you keep), with a new streaming option.
The library accounts usually have limits, but they are per card, so if you have access to multiple cards (spouse, kids) you can download more. Libraries like more circulation, so we always encourage it (yes, I work in the local library).