I used this for a while and it's nice :
but outside your price range.
I've heard good things about this mic from HMC users, I don't know why it wouldn't work on an HVX.
I only mention it because It's been given a rep of being good value for the money, or so I'm told.
on an HVX anything is better than the on camera mic, so any of the mics on B&H under 250 (http://www.bhphotovideo.com/c/search?ci=8533&N=4257447717+4293918168&Ns=p_PRICE_2|0)
will be a step in the right direction. but you get what you pay for, so don't expect perfection at 200$. still, a step up.