My first (and second) device: Astak, was not tied to a single store. It cost US$200 in 2010. My main selection criteria was that it was Adobe compatible (what was used by the local Public Library)
Most of my first book purchases were from Baen and they emailed a download link. I chose Zipped, becausi I used my own computer and had WinZip to unzip. I could have just coppied the EPBS over to the Astak, but I already had Calibre
up and managing my Library.
Amazon's brilliant plan (and it was): No computer required. No WiFi or Internet needed. They used the Cell Network (Whispersync) to shop and deliver