i was thinking about getting a fm modulated mp3/cd changer since they are available on ebay for around 120 and i was wondering how hard one of these would be to install and will it sound like crap since its going through the stock radio?

 

It'll sound as good as the radio does.

Install is pretty easy, you'll just need to run a power line from the battery to the mounting location. you could use interior power sources, but the battery is the better place to use. Otherwise you could be popping accessory fuses

 

You could also go with a Ford CD changer, since the stock single CD and MP3 units have changer controls built in. There are several on ebay between $100-200