I offer a number of DYI or pro-install options which I in fact replaced my Speakercraft business with years ago.
Most of the DYI kits I offer as standard include speakers however I can easily pull the speakers from the kits and just offer a pre-programmed kit which can easily replace what you have on the electronics side of things.
The value in these kits is they are proven solutions which are really designed for anyone to be able to install. And in a situation like yours where you're replacing an existing system, it should be a cake-walk.
Personally, while the most expensive solution, I like our kit which features a Savant multi-room audio system. The big advantage to their solution vs anyone else is their ability to NATIVELY support 4 simultaneous streams of iTunes music in addition to up to 8 inputs of standard analog audio. And with iCloud services, you can always keep everything in sync... even playlists with the pay service... none of this different music or playlist crap depending on device.
That said, we offer kits based on Crestron, Prodigy, Savant & Sonance; Prodigy probably being the most cost effective.
Our kits come complete with system-specific installation instructions and include 1 hour of phone tech support. We have various options for remote monitoring, system upgrades, tech support, etc.
If you're interested, let me know via PM and I can send you some info. Please respond via PM as I don't receive updates to the threads (just don't like to clog my in-box up)
As far as pricing, you might need to share with us what this price range is that you're trying to stay within; simply because you may have paid too much or you may have gotten some ridiculous deal from a company who whored one out the door.