Sorry, Ozzy62, your following statements and it's consequences are off track true when you say ''By going with a large stand mounted monitor + sub, you can get into the mid to upper 30s with the monitor, then have the sub finish the job while locating each where it sounds the best. And if the subwoofer is worth its salt, there won't be any integration issues either''...a lot of nice theory here, and it will get real expensive real fast following this advice.
I do agree that room interaction is critical when choosing ANY speaker not just floorstanders. This is why it is always best (and unfortunately not always possible) to try first in your own room.
What you propose as a solution (monitor plus sub) is a much more expensive and complicated solution than going to a suitable floorstander, or at least one which minimizes compromises. Furthermore, the monitor/sub solution is generic theory at best, and given the context of sensible spending, I just cannot endorse it.
It is interesting that while you point the finger at room interaction as one of the difficulties of integrating a floorstander - it is the very challenging task at hand when working with subwoofers - and for many, it is very hard to achieve this seamless integration to make the speaker sound as one.
You mention that ''...if the subwoofer is worth it's salt, there won't be any integration issues..'' Again, this comment is off track here, in the context of a speaker that has to respect a certain dollar limit (read the initial question again there IS a dollar limit here!)
Now let me ask, at what level is a ''speaker worth his salt''? This is highly subjective. For some, a $ 500.00 Paradigm will fit the bill. My personal take on this, after trying quite a few, is that efficient, seamless subwoofers do not come cheaply. In fact they are quite expensive. Add to this the price of a quality monitor, and you might be way above your price target when compared to the performance of a decent full-range speaker. Factor in the extra work involved in ''matching,' the sub-monitor-room interaction, without any guarantee of success, and you can spend a lot of time without enjoying your music.
If course if you have the money and the time - and some people do - every solution make sense if it makes you happy.