Mcullinan -
Are you going for something more compact? What type of output are you expecting from your sub? What speakers are you trying to match? When it comes to music making sub-woofers, there are a number of options.
If you can accommodate a larger box and demand lots of low end output, the VMPS Larger may be right up your alley.
Taking things down a notch in terms of size and output, recent vintage REL Acoustic sub-woofers have always been well regarded, and often hailed as THE low end music making champions. $1000 can step you into the Stadium III territory, very adequate for medium to larger sized rooms.
A number of people 'round these parts also enjoy the ACI Force (and the larger Titan), a compact sub that is often compared side by side with similar priced REL components with very favorable results. A quick google search (or visit by Lonewolfy) will yield tons of reviews.
Martin Logan also produces a few fast and detailed and well regarded subwoofers
Finally, bringing up the tail end of my recommendations is the fabulous Totem Acoustic Storm - an extremely quick 'musical' sub with a tone that errs more to the warm side of things.
There are many more wonderful products available on the market. The above are just a few brands that spring to mind that retain a reputation for delivering a reliable and consistent product with great performance. Good luck!