Android phones, apps and tablets

Wanted: cheap second hand phone with good battery life, solely to be used for playing mp3s through built-in speaker

I want to gift somebody a phone they can use to play music.
They want a little "radio" that they carry around in their pocket.
I use iPhones myself but they are a bit older and not very tech-savvy so I thought android would be better, to have the ability to just copy music from the desktop via usb, without syncing / libraries, etc.

Ideally:

• with good battery life (even when already a bit older..)
  
• with good built-in speaker (it will not be used with headphones)
  
• readily available for cheap on the used market
  
• all other functions (apart from playing music) are not relevant
  
  

Thank you in advance for some recommendations!