[ps67]

You could buy a ereader without giving it the wi fii password, so no internet.

For example if You buy a Kindle from Amazon it will arrive already with Your account, and when You buy books You can download them with Your PC and then insert in Your Kindle trough USB.

Also With a Kobo it is possible, the difference is that You will need to give Your email to the Kobo to sign and use Kobo Desktop to download books (but also download the books from Kobo site without Kobo Desktop), but no need of wi fii. And there is a patch for kobo for hiding browser (Hide browser from beta features), to avoid temptations.

And of course You can use calibre if You like it.

I talk about Kobo and Kindle because I own them, but I am sure that some similar solution exist also for almost all device You could buy.

It is not necessary to search a old device from nowhere without wi fii feature.