Buying a game console?

i want to buy a new handheld console..my heart is dae set on the nintendo ds-i ,i been holding out fo over a year just to buy a ds..but then i hear it as no gba slot..i dont really care it only affects me in the pokemon department...so i wanted to know..how much is the gameboy advance micro used..i want to buy a used version of the handheld so i can play my pkmn FR and emerald..thats all...i'll worry about transfering to my diamond/platinum later..so how much is a used gameboy micro and where can a buy one..not online...in a store..thanks