Certainly worthy of a mention so thanks for that. As far as I know, they've always had a quad discount that kicks in upon purchase time in the cart.
For those so inclined; Four IB3-18s, combined with the ubiquitous Behringer EP4000, executed in an IB, ..... makes for so serious bang for the buck firepower, ... no doubt.
125dB plus@1m@20hz with a mere 200 watts per driver. Bass is bass, however executed correctly, this yields it's output without the typical compression found in other full excursion approaches, and doesn't possess the time smeared energy emanating back thru the driver. IBs are not without their inherent issues to be overcome as well.