There has to be a point where the $$ spent has no relation to the sound you get. I'm just questioning the point as to when does this get kind of silly..Frankly speaking, I wouldn't know an absolute answer. It gets silly when the sonic result is trivial compared to the investment. In real world terms, this point is usually reached below ¬30k.
The reasons are many, not least because the products (spkrs) out there are often mediocre performers or plain abysmal -- however nice looking.