there are a multitude of factors that affect this decision, most notably what sort of sound quality you are willing to pay for, where (geographically) you'll be using it, whether you'll be using it for voice only, specifially which Sony DV cam you have and it's type of input (balanced or un-), that sort of thing.
additionally, transmitters and the actual microphone capsule can (and often should) be purchased separately. a good rule of thumb is "anything you can buy at the music store, don't"
there are some beautiful sounding mic's out there. Countryman makes some of the best, tho they arent cheap. Shure UHF transmitters are pretty much paramount as far as quality vs. flexibility (if you'll be using them in various locations regionally) is concerned.
email me if'n ya have questions...
:ryan
magnetic1@earthlink.net