alluded to, most mp3 players have the ability to record your voice, along with other handy little features.
Some of these are barely bigger than the cassettes, you're talking about.
Mine, which is no longer in production, records voice, records from any device that has an audio-out jack, and receives FM broadcasts.
It has 512MB of storage (any file type, like a flash drive)
, which can be supplemented with 512MB (max.)
SD Memory cards.
It's as long as my index finger, and uses 1 AAA battery, which lasts 10hrs playing mp3's.
It also came with a FM transmitter that plugs into a car cigarette lighter, so you can listen to your jams over the car radio.
It costs me $34+shipping.
Isn't modern technology wonderful?