Mike's suggestion is good. I have another that might work. I have two new
Tang Band W8-740C 8" Subwoofers up for sale in the classified section. You can mate these up to the same PE amp - or if your handy with electrical and can run yourself a dedicated 220v circuit - get two
Cerwin Vega amps at ApexJr for 55 bucks each...each sub getting its own dedicated amp in a single box...either way, slightly less or just over $200. I haven't modeled the Minstral, but I believe the two W8-740C's would give it a serious run for the money.