Last time I was in the Lake Sumter Villages Yamaha store they had two systems to chose from, both were mounted overhead. This puts the speakers close to your ears so you'll have clarity and won't need to turn the volume way up. They wanted about $450 and $650 installed.
My neighbor wanted one with XM/Sirius radio so he had a system installed by Best Buy, he paid just over $600, and then you pay an annual fee to XM. I have XM in my car and it's well worth it.
If you're just wanting AM/FM and are handy, you can buy the components from places online like BuggiesUnlimited for about $300. Here's a link,
Complete Overhead Radio Kits (Black)
