I have a new sealed gameboy play it loud series in yellow. How much should I expect to get if I sell it on ebay or something?

I am interested in buying a Gameboy micro either from japan or the UK. Cuz they have those cool colors, and since they are region free. But I was just wondering what is the difference speaking of hardware? Is there any? Is the only difference the charger? So if I buy one from uk or japan would I be able to use a USA charger on the Gameboy micro, or would I need to use a native one? Thanks!