My thoughts
I think it's literally in thirds. Those superspeakers you have won't sound all that great driven by a big box loss-leader receiver and source. Those high-end seperates and such won't make a $99 pair of paper-coned particle-board Rat Shack specials sing like the London Symphony. And none of it will sound it's best in a boomy, shrill, echo-ey box of a room. I don't know that you have to actually shell out an equal third for treatment, but as far as research and due dilligence it certainly should have the same consideration.
Answer 1: 33/33/33 Room/Speaks/Equipment and Cables.
Answer 2: I spent less than 2% on room treatment, but only because A) My room was already fairly inert and B) I went to an estate sale and cleaned out probably 2.5G worth of room treatment from an HT room for $500. Bass traps, corners, etc. the whole shebang. Used half of it. Sold half of it on Craigslist.