Velodyne does make decent musical subwoofers, however for the same money, I think you might be able to find a better bang-for-the-buck solution from SVS, AV123's Rocket Subs and HSU. As the criteria you've specified is tight bass, good musical response, wanting to use it primarily for music listening and realistically like to not spend more than $600, here are some options or suggestions I'd offer:
SVS
SVS 25-31PCi ~ $575 shipped
SVS PB10-ISD ~ $460 shipped
AV123
Rocket ULW-10 ~ $560 shipped
X Series x-sub ~ $240 shipped (SOLD OUT until ~7.03.06)
HSU
HSU STF-2 ~ $430 shipped
HSU STF-1 ~ $320 shipped
Outlaw LFM-2 ~$350 shipped (identical to the HSU STF-1)
Dayton Titanic 10" MKIII Kit ~ $358 shipped (requires minimal DIY work)
These are all under $600 shipped, but vary on size. Also, while these are all excellent value subs, their performance will depend on the room you plan to use them in. All of these should perform well in any room less than 2700 cubic feet, but any larger than this, one of these may not be enough for the listening environment... -TD