I still have my minidisc player. Its a Sony webmd i think. Used to be able to get around 80 songs a disc. You could get a 5 pack of discs for $10 bucks, so back before ipods and zunes they were alot cheaper then the memory card type. Thing runs on 1 AA and gets 2-3 weeks of play on it and it's pretty small too. The original software was horrible and slow, they made new software versions that can be downloaded that are much bettter. Some came with a radio.
If you are really bent on buying one, you can still find the discs and players around, Sony made a better version a couple years ago, has more space and is compatible with the old discs. I would look at that if you want to buy a portable. Pioneer and a couple of other companies made some decks that would play the discs. I use a Zune now, 30gb of music, video, pics, wireless and a radio. Hope this helps you out.