I listend once to a little bit with the Yamaha Musiccast line of products. They feature a little in-wall amplifier that sounds very similiar to the A-bus amplifier. I heard it powering a pair of bookshelf NHT's and it sounded pretty good for something so small. I remember them costing around $400 per amp.

As for audio over ethernet, I just worked on a concert that featured all audio tie lines sent via Cat-5 cable via an Aviom network. It worked perfectly and sounded great. Of course, the Aviom spec may be different but it shows what advances have been made in the area.

To get install gear prices, you usually have to work with a store. That store will probably first refer you to one of their installers. I would go around to the authorized Russound dealers in your area and see what they recommend.

Hope that helps.