Cesium offline, is it possible?

I need Cesium work completely offline. So i have terrain server and then i need imagery tiles. As i understood there is no imagery provider with satellite data that can give away this for free. You need to buy it from maptiler, for example. This data would be around 100+ gigs and cost you a lot of money. I need 10-12 levels of zoom.

Here’s more information about running Cesium offline.