You said you are very price conscious. That's open to interpretation :-). On the other hand you are mentioning systems that are not what i would call budget systems. So I am not sure what options to give you. The things you want are not things I'd equate with budget systems, that's for sure.

The other challenge to answering your question is it's sort of like answering "what the meaning of life". If you said I want sound in 6 rooms with a keypad it's easier to answer.

That said, if this is going to be DIY or you like the advantage of "not proprietary" by which I'll assume you mean anyone can have it and so forth, you may want to take a look a CQC (www.charmedquark.com). It is very powerful automation software. It is NOT a multi-room A/V system, rather you would use it to control one. That is one place you might look. Crestron can of course easily do all that you want.