I have found that sharing my library helps defray costs - my mom, grandfather, partner and I all share one library, so we only buy once. I'm sort of the default 'curator' and buyer of most things, but mom has bought one or two, and grandfather has, too. Nook (like most e-book providers) has lots of free content available, and she can also use Project Gutenberg for public domain stuff.
I wish my MIL would let us buy her one - she's mostly blind, but if she has it on the largest text size, she can read. My grandfather (in his 70s, but really healthy) has said the small size of the nook simple touch he got has made it possible for him to read for long periods again - he used to get arm pain from holding the large hardbacks he likes to read, since they are large enough print to be easy to read.