1. https://tehnoetic.com/ 2. https://minifree.org/ 3. https://www.thinkpenguin.com/ 4. https://vikings.net/ 5. http://www.libiquity.com/
Tehnoetic is the best compared price vs specification. First in delivering mobile phones based on free software Replicant. Adding some LibreCMC routers on your shop would be a great deal.
