Tello has launched a back to school offer which features a bundle deal of $20 off select phones when purchased with any phone plan.
A total of 5 phones are being sold as part of the promotion by the Sprint MVNO. Phones that are included as part of the offer are the Huawei Union ($29), LG Tribute 2 ($49), HTC Desire 626 ($49), Kyocera Hydro Reach ($55), and ZTE Warp Elite ($69). All phones are refurbished models and a bit older devices.
I did a quick search for most of these models around the web and pricing with the discount falls inline or slightly less than what you can get the devices for either new or used from elsewhere. Most devices are sold around the web as Boost Mobile or Virgin Mobile phones and when sold as new they must be used with their respective providers and can't quickly be taken to another MVNO.
In addition to the 5 phones mentioned above, Tello has the Alcatel Cinch available for just $5. The Alcatel Cinch is an older feature phone.
Tello is a Sprint MVNO that offers its customers the ability to custom build their own cell phone plans. Subscribers choose from separate allotments of talk, text and unlimited data with their chosen amount at high speeds before throttling to 64 Kbps. Data only cell phone plans can even be purchased as subscribers are not required to pick allotments from all 3 types of service like you are from most other providers.