Boost $25 unlimited plan

Seems decent if sprint works for you and the free sprint plan isn't something you can or want to sign up for. Though getting a valid phone is challenging with boost (says ex sprint devices not eligible).

$25 a month unlimited inc 8gb hotspot and 50 mins of voice roaming.

https://www.boostmobile.com/plans/bring-your-phone-25month-unlimited.html

Pay for it with cellnuvo gold. New or port in customers only.

Thanks mmfacemm for sharing. Do you, or anybody, know if after activating Boost/Sprint service on an unlocked phone, also compatible with GSM, one can replace the Boost/Sprint SIM with, say, active AT&T SIM, and the AT&T service would work?, ...and return to Boost/Sprint service by replacing the SIM again?

Yes. You can switch SIMs and it will work.