Do you have basic woodworking skills? If so, I can throw you some plans for a ported enclosure. A sheet of wood, some screws, and some wood glue should be attainable for under $50. Honestly, a single decent 12" ported, such as a Skar VVX or a Sundown SA series or an Obsidian, will outperform that Dual bandpass.... by far. Single SKAR VVX-10/12/15 Custom Ported Box Package Deal - Car Audio Classifieds check that page out... a single vvx 12 with a ported box built to YOUR SPECS. While it is a bit pricier than the bling-bling Duals, the performance difference is night and day, I promise you. That amplifier will suffice, since these drivers I've recommended only need 600 watts. As far as that prefab 4th order... yeah, that's really a joke once you start looking at proper bandpass enclosures.... they're big.
