The other day I ordered a book I've been thinking of getting. Ordered it from Amazon. Or rather, ordered it from one of those countless third-party booksellers who offer used copies for sale via Amazon. The precipitating factor was, I received a gift certificate from my brother. So I up and ordered.
How different this is from years ago, when I would've added that book to my floating mental book list, and waited probably years until I stumbled across it in a used book store. If it ever turned up. Twenty, thirty years ago there was no shortcut. Just keep looking and waiting. Fortunately I knew and visited a large number of good used book stores in the part of the country where I lived then. But even so, the time it took to find a book was often measured in years. Sometimes many years.
Nowadays the only real constraint on book hunting is my budget. Because almost any book I may think of getting, I can turn up online in a matter of minutes. And it's that way with a lot of things I buy. Living out here in the middle of nowhere, finding and buying items, even obscure items, is orders of magnitude easier than it was for me living in the city years back.