A2+

I'd be looking toward CDs. Any thrift store should have a pile of CD or DVD players, any of which would work just fine. You'll also need an amplifier or powered speakers. You can either buy used or get something like Audioengine A2+ and you're done. (they have zero bass but get everything else right

As someone who just got a sub to pair with my Audioengine A2+, I'd say its very much worth it to get one for a stereo set up. Music now sounds much more complete and fuller and more real. I guess it also depends which speakers you have as the ones I have really can't dig deep so a sub most definitel