I'd look at Hsu... Dual Drive VTF-2s:
Introducing the VTF-2 MK5, the epitome of affordability and value in the renowned HSU lineup. This subwoofer is designed to cater to budget-conscious enthusiasts without compromising on quality or performance. Most affordable and budget-friendly subwoofer One of the smallest subwoofers so it...
www.hsuresearch.com
Its a little over your budget when you add shipping, but the ultimate payoff is going to be the better option. Hsu Subs are by far the best bang for the buck. These will seriously outperform the PB1000s as a pair and come in affordably below the cost of 2 PB or PC 2000 Pros.
In short, these are Subs you can live with for the next 10 years and not be wanting for more!