I have mentioned this before about the Paradigm PS-1000, it is tunable. It sounds better (to me) if two ports are closed.
I couldn't agree more about the AR 8" subs, they are a bargain. I have one and it rocks for what I paid for it (decent dinner for two price
). I used to have a Sunfire TrueDud and it sucked......a lot. It went deeper than the AR, but it was just too difficult to place and it never sounded right.
I have also had an HSU STF-2 (wish I still had it), and it wiped the floor with the Sunfire. The only sub I have owned that can beat the HSU was/is the M&K which is again out of service (stupid Sanyo IC doesn't like difficult loads
)
So my next venture may be an SVS, or maybe a Rythmik sub.