But why not do the upgrade so you can have more music? It really shouldn't be all that difficult to get all the music you have on a cassette onto an MP3 player and for someone to show you how to use it.
Instead of about twenty songs you could have maybe somewhere close to 200k. Depending on the MP3 player. Plus there's no A side B side. So you won't have to do the flippy thing and there will be twisting and breaking of the cassette tape.