Keep in mind that the layout of the wiring is what's important, not the OnQ (or whatever brand)hardware.
The most important thing is to do "home run" wiring (i.e., all coax, telephone, and Cat-5 terminating at a single location, without splitters in between). If you can get them to do this (including trimming out the outlets in each room) & let you put in your own splitters, ethernet switch, etc. at the central "hub" location, you will be best off.
Depending on the configuration, the cost of the OnQ hardware isn't that big of a deal, in any case. If you want to know where to find pricing of all of the various OnQ components online, let me know & I'll point you in the right direction.