Radio swap out is very simple, Philips screwdriver and 10mm wrench is all you need. I think those radios have an anti-theft code system so if you buy a used stock radio be sure to get the code. It'll probably cost less to put in a basic aftermarket unit with a CD player and aux input, but if you're using the stock keyless entry, part of that system is built into the stock radio.

 

..You could do what I did..I went to a pawn shop & got me a CD player with MP3 for $35. Had to install it myself..I thought it was hard at first but after a while of looking at what wires go to which(radio didn't have Harness) I just cut a few wires & matched all the color wires(red-red, white-white, orange-orange, etc), twisted them together, taped the exposed wires up & I was happy!
If you decide to do it yourself..just remember..unplug the negative cable from the car battery..or you might see some sparks from those wires.