Thank you for the replies everyone.
I have been searching for a new sub for a while, but am looking for a good price over urgency. I would be willing to go to $500 and am looking to get a sub that you can physically feel. The most fitting subs seem to be SVS pb-1000/2000, HSU VTF-2 MK5, or Klipsch R-115SW.
The def tech sub is located a fair distance away, so I will probably continue the search unless they come down on price.