Prosumer camcorders sell like computers. They are constantly being upgraded and constantly increasing in price. So, in a few months you'll be in exactly the same situation, just a bit older. You could wait a few months before buying a camcorder but the result is a few months not making movies. The only thing I would hold back on is buying memory cards, they will fall in price. Only buy the amount you need now.
If you buy a PMW EX3 and you are a serious videomaker, you will grow into it. Whatever you do, it will be "current" for a couple of years at least, probably longer. It is a superb bit of kit and I wish I owned one! my suggestion is: If you can afford it, get it.
As for "Do I need it?" Well, my kit room is full of gear I don't "need" but I find that, if you've got it, you use it. If you have a decent camcorder, you'll go and video stuff. If you don't have a camcorder it's a lot of effort to hire kit for that short "experiment".