>Is it necessary to spend $1000 per speaker or over to have audible, palpable, appropriate bass reproduction?
If you're buying new through normal retail channels it is.
You have to move four times the air to reach a given SPL for each additional octave of bass extension. The only way you can do that is with a bigger driver; which in turn isn't going to have acceptable dispersion at high frequencies.
IOW, you need a 3-way design although sub-woofers can count if the mid-bass driver is big enough and you get good integration.
Going from a 2-way to a 3-way can double the driver cost and triple the price tag on the cross-over network (the mid-range now needs a high-pass filter too, and the reactive components are larger and more expensive than between the tweeter and midrange due to the low frequencies).
>The salesman also mentioned that for high end audio a separate subwoofer is not appropriate as it "doesn't track."
Not using a SPL meter to match output levels will make integration difficult. Trying to cross a ported speaker over near it's low-end roll off is unlikely to work well due to what's happening with its phase there. Adjustable phase or a time delay on the sub-woofer will help. The ability to use asymemtric high and low-pass points may help work around room issues. A cross-over an octave above a ported speaker's bottom end roll off will work. Fourth order electrical low-pass on the sub-woofer with a second order electrical on a sealed main speaker that matches its roll off works. Second order electrical low-pass on the sub-woofer and relying on a sealed speaker's natural roll-off works.
>To cover this fully, doesn't putting the amp output into a sub's crossover to be split to satellites compromise imaging etc?
No provided that you're using a sub-woofer (not above 80Hz with a 4th order cross-over; a Bose "sub woofer" module iwhich runs up past 200Hz is a woofer not a sub-woofer), it's not distorting, and its port isn't making aerodynamic noises.