Yeah, but the MAKER has to pay a $200 tax just to produce an AOW.
That's why the little buggers are so expensive, even though the Serbu Shorty, and other similar short pistol-gripped shotguns, are made on inexpensive Maverick or Mossberg "Cruiser" base guns, as a rule, or sometimes on the Remington 870. Any of these would cost around $200-$250 if bought with the 18" barrel.
When the buyer acquires the gun, he pays $5 NFA Class 2 tax, but the actual AOW is always disproportionately expensive as purchased from the original manufacturer, because the maker has to recoup his payment of the $200 tax paid for manufacturing the darn thing.
If you buy one of these which has changed hands several times, you may be able to get it for a reduced price, since the original costs will have been "absorbed" to some extent.
Then, paying that $5 tax seems like a bargain!
Best.