[remedan]

The Amazon Kindle does a version of this. They offer a more expensive ad-free version and a cheaper one that displays ads on the lock screen. I have already chosen twice to pay more for the ad-free model, and I'm glad to have been given the choice.

[LeafItAlone]

FWIW, I have one of the the ad version Kindles and rarely notice the ads. And the ones I have seen are not even close to anything I would want.