Subwoofer budget max $700: new vs used, brand?


I need some input regarding a subwoofer purchase. I have a budget ceiling of $700 for a powered sub. My system's front end is digital, and I use a modest tube amp with Legacy Monitors. The system is used in a difficult room-vault ceilings, asymetrical wall placement, etc. I'm looking for something musical, not earthquake replicating. My musical tastes are eclectic: pop, rock, jazz, rap, folk. Aesthetics are probably not a concern as the speaker will most likely be placed out of sight.
Should I go new vs used for the best value?
Does a "self equalizing" speaker offer that large an improvement over a speaker integrated by ear?
Brand and model suggestions?
Thoughts, please.
rabco
Long story short, I did not buy the Velodyne Dls-5000r.
At Larryski2's suggestion, I checked out the Outlaw line, and went with an LFM-1 EX.
I'm pleased with my integration efforts and very happy with the product. The Outlaw folks were great to work with, and the speaker was worth the 6 week wait to obtain at it's pricepoint with no charge for shipping (90lb speaker!.
Coupled with the addition of a Cambridge DACMagic to my system, my system finally has reached a more musical, fatique free character despite it's digital front end.
Larryski2, thanks for the suggestion!