
Those stereo stores trying to make a buck once more *sigh*
Those are not poor subs, but not necessarily sound quality subs. I figure he is charging you about 150 for one of them? They are anything but the audiophile sub though. As far as DVC and SVC go they denote the number of voice coils the sub has, to keep it simple, it gives you more flexibility when it comes to amp and using multiple subs.
A few suggestions...
Elemental Designs 11 or 13 Kv2
www.edesignaudio.com
Diamond CM3 10 or 12
www.diamondaudio.com
Adire Shiva 12
www.adireaudio.com
Adire Koda 10
www.adireaudio.com
You are then going to want to build or have a somewhat small sealed box built, I would recomend shying away from a prefab box because they usually are built pretty poorly and are very expensive.
The amp will depend on the sub you choose and your budget, so give us a bit more information and I would be more than happy to help you out.