I am wanting to take out the 3.6v coin battery out of an MP3 player and hard wire it so it never needs a battery. Cheaply and easily preferred. Have a few ideas not sure if they will work. My electronics knowledge is fairly basic.

Option 1 5v unregulated cell phone charger with two Zener diodes in series.

Option 2 Resistors in series and paralell with the MP3 player to not only get the proper load for the power supply but also the
correct voltage to the MP3 player. (Yes inefficient and would take a lot of trial an error)

Option 3 Regulated power supply close to the required MP3 player voltage. (Everything I have found isn't very inexpensive)

Option 4 Something I haven't thought of! Thanks guys!

 

I would use something like this connected to your 5V charger.

 

Thanks for the idea tracecom. But unfortunately I don't think I have the knowledge, or time to build that.

 

Option 1 5v unregulated cell phone charger with two Zener diodes in series.

That gets my vote for cheap and simple yet effective, except that you don't need zener diodes, just regular silicon diodes. Each will drop about 0.7V. They must be rated for the current your player draws, but since a 1A rating is pretty normal, that should be no problem at all. Anything powered by a button cell uses far less current.