Is your dash hacked up? If not, your radio options are limited by the fact that the stock radio buttons and dials slide through those dash holes. You can have your old radio refitted with new am/fm parts and an AUX port, but that is expensive.
Of course, if your willing to cut the dash a new head unit can be had to $100.
How many speakers are currently in the car? They make kick panels with speaker holes, your package tray may have speaker holes. There is a member on here who sells brackets to fit two small speakers in the center of the dash to replace the mono-speaker.
I use a cheap rechargeable bluetooth speaker that I stream music to from my ipod. Not great, but a cheap alternative to get you down the road. There is a pic in my scamp page in my signature.