Amazon's Prime day deals may only be for Prime subscribers, but they're not the only deals the retailer is offering right now. Over on Woot Amazon is selling Kindle Paperwhites and Kindle Voyages at steep discounts.
Right now you can get a Kindle Voyage refurb for $75, or first or second gen Kindle Paperwhites for $25 to $35.
Of the three, I would say the best value is the second-gen Paperwhite. It can run the latest firmware with all the best features, and yet costs less than half the price of a Kindle (2019). That is a great buy, IMO.