Matrix -
I don't know of any speaker that meets all of your criteria!
You see, there are tradeoffs between bass extension and efficiency that make it fairly difficult to find a 92 dB efficient speaker that truly goes deep in the bass within your price ballpark.
Speking of tradeoffs, in general small speakers do the soundstaging thing well, while big speakers do the bass/efficiency thing well. Getting both, once again, is fairly expensive.
And while there are technologies that make a speaker very forgiving of placement, they are also generally outside of your price ballpark, and don't include any 92 dB efficient speakers, to the best of my knowledge.
So, let me ask you a few of questions.
First, what exactly are the problems you anticipate as far as speaker placement? Boomy bass? Early sidewall reflections?
Second, if you can't have both deep bass and fairly high efficiency, what kind of balance is acceptable to you - in other words, what are you willing to trade off?
As far as soundstaging goes, are you looking for superb imaging for one person, or pretty good imaging over a wide sweet spot?
Best of luck to you.