At $2k subwoofer budget, definitely get at least two subs. The SB-3000 is a fine sub, but I would go ported if possible. Don't worry about people talking about unwanted sounds coming from a port; most of the sound that a port produces are ones you want it to make. It can make unwanted sounds only if you push it really hard- and that would be a point at which an equivalent sealed sub would be making much worse sounds.
In a $2k budget, I would be looking at a dual setup of Outlaw Audio Ultra-X12, Hsu VTF-2 mk5, Monoprice 12" THX Ultras, SVS PC or PB-2000s. If you can stretch your budget a tad, look at dual Hsu VTF-3 mk5s (small discount for duals can be had
here).