03 Mits Eclipse GT

Can anyone tell me since I am new to stereo install. They told me at best buy that it was very very hard to install an A/M kenwood stereo in my eclipse due to the infinity system that is already in there. My wife wants sirius satellite so I bought a kenwood head unit with sirius. They told me it would cost at least $150.00 to install because it would have to be all rewired. Can anyone give me any suggestions or should I just pay the money and be happy.???????
Thanks Michael:bloated:

many of the new cars have stereos with built-in external amps and the such ...... sometime meaning you have to completely rewire things to put a new stereo in.