A $3,000 sub is better than two $200 subs but two $200 subs are better than say a $750 sub if they're placed nearfield.
My cheapo's were Infinity PS10s and the better subs were a Def Tech Supercube 1 and a RBH 1010-SEN that I tried individually as replacements for the dual set-up. Single subs nearfield are a little too localizable (is that a word?) even with a lower xo and timing tricks to make it less so.
The $3,000 beast was a PSA dual, sealed something or other that I got to hear in a friend's system.
But then again, an Epik Empire (~ $800) had enough output to keep up with $10,00 towers in a different friend's system.
So I guess it depends. Final Answer.