Women are all different, so there is probably no single perfect solution. I just started building mine without any kind of committee meeting, but I also have them here in a room that is all my stuff. If you have to keep it in the living room, it might result in the compromise/abomination commonly referred to as The Furniture Cab, which is still slightly better than nothing.
I wouldn't dwell on the cost, and keep her out of it. You can spin it that you already have the spare PC to minimize expense, but I'm working on my 3rd cabinet, and I can tell you that every time, the stuff not initially considered like special tools, brackets/hardware and other detail items will nickel and dime you to death. Its nothing to drop $90 for brackets, hinges, paint, paddle bits and other small things you need to work around problems as they arise. It's less and less with subsequent cabs, but the first one is a killer.