Subwoofer choice for noob

Hi guys. I'm new to the forum and new to the world of home audio. A few months ago I got a great deal (or so I think)
on a set of Klipsch Synergy speakers. I paid R7700 for the set and got it on lay-bye. And about two months ago I
bought a second hand Cambridge audio 340r Receiver to run the speakers. On the whole I'm getting the desired sound,
i.e. good mid bass, reasonably neutral and no harshness on the treble, I think in part due to the CA receiver.

Now, I need some buying advice on a subwoofer. Soon, I'll have enough cash to buy a subwoofer, but my choices are
limited because of budget and location. My budget is about R4000, and I would at least like a woofer that could cleanly
go down to about 30hz. The F2 towers are doing a great job with lfe and music. I need the sub to sound great with movies,
not so much with music. I prefer having music two channel and so far two channel listening has been great.

What I have looked at so far: Velodyne VX10(a bit too small, but cheap), Velodyne CH12R(slightly out of my price range),
Polk psw12(Not too sure about the polk subs...), and my favourite candidate so far, a Wharfedale SW380(15 inch, sealed).
The wharfedale is from Hificorp, so I'm not too sure about it.

Thanks in advance for any input.