I can vouch for the maker of the enclosure your thinking of buying. I bought a box from him and am very happy with it, quality construction all around. But the sub choice.....
Go with a well known brand and you can't go wrong. Infinity (which I'm partial to) Alpine, Eclipse, all make subs in different price ranges to fit everyones budget. Try to listen to some subs before you buy, that way there are no surprises.
IMO, one high quality driver with the correct enclosure and amp in a Ranger may be all you need. Just my opinion of course!