Refurbished Logitech MX Sound Computer Speakers | $39 | Amazon
Right now, you can pick up a refurbished Logitech MX Sound audio system for a a low $39, or $60 less than buying it new.
In addition to connecting to your PC with a 3.5mm cable, the MX Sound also includes Bluetooth to pair to your phones and tablets, with one-touch switching between devices. And not for nothing, they happen to look way better than most computer speakers, which matters for something that sits out on your desk all day.