This SVS should fit the bill!
Don't know the starting prices for Hsu and Outlaw, but they are two companies, (along with SVS), that are specialists in high quality budget subwoofers.
I believe SVS has a generous trial program (45 days in home with free shipping BOTH WAYS!). I'm not familiar with the Hsu or Outlaw in home trial.
SVS also have a nice tool, (Merlin), on their website to match your speakers to their subs, it is fairly exhaustive in terms of main speaker listings, but I don't think your speakers are on the list. I would give them a call at their 800 number and get a staff recommendation. The online tool not only acoustically matches several sub choices to your main speakers, but they typically are a good match "budget wise". My take on SVS is they don't try to oversell. Another option is to try a couple of Pioneers, or Dayton subs (Parts Express), as two subs should provide
Whoops sent my response off before it was finished by mistake.
Two subs may help achieve a smoother in room response and more output. I would be surprised if the two "cheaper" sub option would be as well built as the low end SVS or HSU subs. I would also compare warranties, vendor knowledge/advice and tech support.
Well, yeah, I realize that, donvito101. I had some questions and they answered them. I also called Crutchfield and had a chat. Went with the SVS, go figure. They had one available for $450 (open box, brand new otherwise), so I got an Audioquest cable, too and still came in under $500. That'll do!
RELs are brilliantly designed, sound great, and use your main amp for the signal (the "High Level" input...so they arguably sound like your amp). I own 2 from the same era…a Q150e 10" 150 watt, and a Q108 MK2 100 watt. Both were bought used for around 200 bucks each and work perfectly, and feature adjustments for level, phase, crossover points, etc., that many other brands don't have. They're known for their "musicality" and having had mine for a while used with various power amps, I can say they're an indispensable part of what is the best sounding rig I've owned in over 50 years. Be patient and look around for one of these as you can't go wrong with 'em.
I strongly suggest a Vandersteen 2WQ. On-board 300 watt amp, adjustable, allows your amp to work solely on your mid and treble, and clears it up considerable. $1m600.00 but you can find previously owned for $500.00. I did. If in S. California, try Stereo Unlimited. I think they have one., so you can listen to it. Otherwise, they are often on Audiogon.