This is to see how cheaply you can make a am radio.
Basically this really is "how to make a xtal radio set or fox hole radio"

Main parts you will need to find
1 Some kind of ear phone. This is a must and you can't make one, well at lease not easily.

2 wire, small in diameter and the longer the better. this item to is kinda hard to make.

3 a diode, A manufactured one would be great, But this is something you can make from stuff around the area.

So, this is the minimum number of parts you'll need. Remember the goal here is to make a radio that works, How well is another story. Getting the radio up and running then upgrading the set one part at a time is another possibility.