which sub to add to vandy 1C's

Looking to add a little tightness and speed to the bass on my vandys, it seems a tad too laid back for me on certain rock recordings. Of course I want it to integrate well with my current setup (nad 320bee and vandy 1Cs). would love to get the a 2WQ but unfortunately its a little out of my price range. I want to spend $300-$500. room dimensions are fairly small so i don't nessesarily need the most powerful sub. I've considered upgrading to the 2Cs but think adding a sub makes more sense as i am completely satisfied with the highs, mids, soundstage of the 1Cs, especially on jazz and more accoustic recordings, just missing that extra punch that i think a sub would provide. thanks.