Purchasing books (e- or otherwise) and audiobooks is an expensive proposition, especially if you don't necessarily want to add them to a real or virtual collection for revisiting. This is one way our public libraries can come in handy. But did you know you can get many titles for free without even leaving your home?
Overdrive Media Console (free for iPhone, iPad and Android) has been around for some time, but has improved with its own updates for usability, in addition to the increased availability of e-materials through public libraries. Overdrive allows you to sign in to your local library with your login and password, then download or join waiting lists for e-books or audiobooks, all for free.
E-books can be quickly downloaded with a few taps and added to your Kindle app, while audiobooks (download while on wi-fi to avoid data charges) play in the Overdrive app themselves. This is the perfect summer app for you to grab a few titles for lounging on your porch, or perhaps an audiobook or two for a long drive. The only caveat is that you have to finish the title within a set period of time (in Boston, two weeks) or it disappears from your library (i.e. is returned). This is one reason I tend to use the app more for nonfiction, so I won't remain in suspense should there be a wait to re-download the book.
Currently I am working my way through my (2nd) download of Malcolm Gladwell's David and Goliath, in which he argues that what we perceive to be advantages and/or disadvantages may not actually be. In one chapter, he details the many people with dyslexia who have gone on to great success because--he claims--of the other qualities they have needed to develop, such as resilience and listening skills. Though certainly there are tons of people who have overcome learning disabilities to achieve wonderful success, I'm not sure I bought the "dyslexia universally helps you" argument at all (naturally, this chapter was controversial and spawned some criticism). However, Gladwell tells a good story, and I am glad I didn't have to pay $20 to read it, considering.
Overdrive is also a handy tool for SLPs and support teachers of any kind for free access to curriculum contexts such as books being read by our students in their classrooms. Over the years, I have found audiobooks to be a great way to utilize my commute time so that I could be on the same page, context-wise, and construct activities for my students when their classrooms include chapter books such as Number the Stars.
Do note that my experience is based on using this app in conjunction with a membership in a large urban library, and I am not sure how your connections will serve you. However, I have seen this app recommended at workshops and elsewhere as a great resource for e-books. Hope you find a few free books to pass your summer time!