best subwoofer for less than $1000

First, several questions to you:
1. Are you going to use the subs mainly for music, for home theater, or both? If mainly for music, what kind of music will you listen to?
2. Do you want a powered sub, or one driven by external amp?
3. What is the low frequency response curve of your main speakers?
4. How large is your listening room?

Thanks.

Used REL Storm.....no comparison for the money IMO

Used Alon/Nola Thunderbolt. Very fast, tunefull and deep true bass. Fast enough for planars or stats.

Would you consider $1050?

After all of my research and auditioning, I will soon purchase the ACI Titan, although I have not heard one yet. $1050 for the basic model (plus $20 for spikes) with free shipping until Dec. 31.

response to Sdcampbell
*i do 50% music and 50 movies so the sub miust be able to do both well. I own nearly 1000 cds and listen to mos of them in all genres
*I want a powered subwoofer (easier fiddle with for me)
*main speakers are wharfedale opus 2s and go to 30Hz comfortably.
*my room is 28'L by 22'w with 8' ceilings