Currently I have a Klipsch R-12SW, and an Allison Al10.
I think I'm going to sell/get rid of the R-12SW, and keep the Allison AL10 a little bit until I manage to scour the used market and find a pair of subwoofers. The Allison is rated to lower frequencies than the Klipsch, but the Klipsch is certainly prettier.
Now onto what I'm looking for: I don't want to spend more than $400 (for two!). I disagree with Gene on this, I believe stereo subwoofers are a requirement, at least for music listening. As such I want them matched. There is no way I can spend what some of y'all are on subwoofers.
To achieve this, I will have to scour the used market, and likely pull all the tricks I can (scan the nationwide craigslist and ask for shipping, and/or ask someone to buy something for me).
It's very difficult to find two subwoofers for sale, so I'm thinking of finding a good deal on one that's reasonably popular/available, and then getting a second. For example, right now there is someone selling a Pradigm PS-1000 subwoofer for like $150 (I'm not sure which version), and I could get that and then scour for a second. Unfortunately, this is a relatively rare model, and there are many versions available.
The research I've done has taken me here:
speakers, user reviews, editorial reviews, speakers deals, used speakers
www.audioreview.com
Finding best of the most reviewed subwoofers. Since there are a lot of reviews, I expect these to be reasonably popular, and I might be able to find two that work. Another route is to actually build my own, which I'm more than capable of doing. Actually, I just got done with a huge woodworking project, and my next project is all Electrical work, so I have literally anything I could need for electronics work and woodworking.
Please refrain from giving me the "No such thing as budget and good". If I had a lot of money to spend on subwoofers, I wouldn't have the time to enjoy them.