Any used options for you LougeRat? Never a bad idea to check Craigslist, you might be able to find a good deal there. I larger sub will often give you better performance than 2 smaller ones, better quality sound and extension as well.
I would look at the SVS PB-1000 for $500, rather than 2 cheaper Klipsch. Hits 20Hz, and better quality. Probably higher SPL than the 2 cheaper subs you have been looking at.