I often download free public domain books, and read them (but not always).
I sometimes download free contemporary books, but I am less likely to read it than a book I purchased. That's because before I purchase a book, I make sure I actually want to read it. If it's free, I may download it "just in case" and forget about it. Also, it's hard to disconnect the link in our mind to the intrinsic value (if there is such a thing) or something and its monetary value.
We tend to have a bias toward being happy with something bought for a relatively high price, and being unhappy with something free or cheap. Anything that can be gotten for free, or very cheap, is automatically degraded in our mind, or at least suspected of having low intrinsic value. Of course that judgment may change with time, but you start with a negative bias.
In short, the statement "You get what you pay for" is true, at least in our minds.
I have downloaded and read several free (contemporary) e-books. I'm not sure how many, but probably around 15-20. I can remember only one case where I bought another book by the same author. Many of these books were just bad, to my taste, or at least not good enough for me to seek another. But some were OK and a few even good. If I had paid for those books, how would I have judged them? I honestly don't know, but I am pretty sure that the price I paid them (nothing) played at least some part in my negative response to them.
So, even though I checked "I base my purchases on content, not price", this is not 100% true. There are books that I don't purchase because they are too expensive (especially e-books; I am more ready to pay a high price for a paper book, even though I prefer to read e-books - go figure

). There may also be books that I don't purchase because they are too cheap.
Sorry if this sounds a bit confused, I am only trying to be honest, and honestly I do not know how much the price
really influences my buying decisions. I just know it does