Well if you have a junk yard near you or find someone selling there oem one here, that would be a cheap alternative. I bought a 6 disc version for 30 and sold my single disc for 20. Ebay sells them at a crazy high mark up, so dont buy there. It would be a straight unplug the old one and plug in the new one.
You will most likely need a wire harness to connect the aftermarket unit to your stock wires/connection. Our cars use a double din style unit, so if you get a single din, you will need another piece to fill the gap and mount the single din unit.
will have all the info you need, just type in your car information. You dont have to shop there or anything but it will list what parts you need for whatever head unit you want to go with and is a good resource