The really expensive subs like FB Audio Neos (Upwards of $1799 per driver) are expensive with the following end result-
They will destroy any Ferrite based motor on output as we have tested against sub close to $1,000 using Ferrite motor and result wasn't even close.
TS parameters show the Neo is over 200% more efficient than all other Ferrite design in FB Audio lineup so comparing apples to apples, you can a LOT of output from a single driver.
When comparing Ferrite to Ferrite, the same thing applies. That is why you have 100wrms subwoofers and 5,000wrms subwoofers.
In car audio, paying more money offsets one of the following characteristics to gain another-
Weight
Cost
Performance