Pocket pc Ipaq. Need a regular sd card and some sort of reader. (most only do basic functions anymore being so "old") I use a mini sd and a sd converter part. Its pretty easy to beam things over. Almost instantly picks up the tamagotchi. You beam using a simple task. Unfortunaly, you will likely need to keep the Ipaq plugged in, mine does. If you keep it charged and use say, your phone sd card, it will save the last files loaded if you remove the sd card. (if it keeps power that is)
Most of the time you can find some decent prices. Make sure you get a usb with it or its useless tech... I have one of the first release ones, if that helps. Its your ancestor of the iphones/ipods/itouches... Etc.