Sumiko seems to charge a huge markup for importing RELs. Frankly the price of new REL subwoofers is not competitive here in the US. I own a Strata3 which I bought used for $800, and for the price I'm very happy.
Other people have recommended ACI for home-grown subwoofers. They make a titan sub which is apparently pretty good, though cannot cross over as low as a REL (Though I doubt that would be a problem crossing with 805s, since they're pretty small speakers).
REL also makes the Rega vulcan ... perhaps that will still be imported.
I have also heard good comments about the Ruark Log-Rhythm subwoofer.
Lastly ATC makes an active sub, but I don't know if it's available in the US. And so do Linn. Their sizmik is quite well reviewed, but, again quite expensive.
Other people have recommended ACI for home-grown subwoofers. They make a titan sub which is apparently pretty good, though cannot cross over as low as a REL (Though I doubt that would be a problem crossing with 805s, since they're pretty small speakers).
REL also makes the Rega vulcan ... perhaps that will still be imported.
I have also heard good comments about the Ruark Log-Rhythm subwoofer.
Lastly ATC makes an active sub, but I don't know if it's available in the US. And so do Linn. Their sizmik is quite well reviewed, but, again quite expensive.