cheap rooted android phone security based

I just want advice on the best option (IE cheapest) android phone that would probably follow the guide and have the apps at [login to view URL] (so pretty simple). The cell phone providers number should never be used. I have private google voice accounts that would be the only numbers used when txting etc. (the google voice account wil be completly untraceable to the phone user.) I guess you could say that possibly it would be the kind of phone a drug dealer would find very handy to have. He can also call his friends completely encrypted when they have the same phone. the apps are pretty simple, you wouldnt have to follow the tor guide to securing android. ill be selling these online as I have had alot of interest so it may be an ongoing project that we can refine. I may get a website for it depending on sales. They need a regualar cell number so people can contact them conveniently. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX just advice on best phone for the job (and it should be easy to root) thats the priority but I have lifetime accounts to all streaming services (us based) that i would like to install on a rooted tv box.