You should start here, as this is where the (subwoofer) crazys live.
The easy starting point is:
$170 + $200 + $90 + glue paint, wire, terminals, fill ~=$500
This is as simple as it gets. Knock-down box that you assemble. Driver's a drop-in but you will have to cut a hole for the plate amp. A drill, jigsaw and screwdriver are all the tools you'd need, plus glue and paint/sandpaper. I've made diysoundgroup's boxes before; excellent quality - duct tape is all you need to clamp them while the glue dries. This driver is new but very capable, and at a good price. Chose the amp by price too, on sale this month and well suited to this driver.
With a 3 cu ft box, F3 is 32Hz and F10 ~20Hz. In your size room, the lowest supported mode is 35Hz (16 ft. half wavelength), so you're well into room gain by the time the sub starts rolling off. Should be a good match without using any active boost.
Just be aware that there are a dozen "good matches" to your request... this is only one.