System stereo for 1999 Monte Carlo?

Recently I have purchased 1999 Monte Carlo for my 1st car and my disk player started messing up it skips and says error on every CD even the ones I just purchased today......I just wanna know when I buy a new car stereo is it best to get it professionally installed or let my friend who does it for $60 do it....let me know prices and and estimated cost PLEEEAAASSSSEEE !!!!!!