Changing coil spring insulators/isolators?

I just bought a 1994 Ford Mustang (base style) and it hasn't been used much recently. The guy I bought it from says it would be a good idea to change the front coil springs insulators as there is a lot of screeching going on when I make a sharp turn. My question is, has anyone had to do this and what was the approx. cost to have it done by a mechanic? I found this set at Autozone but I'm not sure if that would be the right thing and if I need to get one or two sets. Here is the link for the insulators- http://www.autozone.com/autozone/parts/Energy-Susp... Thank you for any input!