Usually I am one of the nice guys here, but in this case, my opinion is much like ittigger's.
Does that mean I'm not a nice guy?
Seems like DJing will be a dalliance for you. If the water turns out to be too cold or the pond is too crowded, you will step right back out. And from the very little info you have provided, you can't expect much solid help to come back to you. At the absolute minimum, you need to know the minimum and the maximum you want to spend on starting your "business". Obviously you haven't even started a business plan, yet, or you would at the very least, know that much.
I do agree with this part - and I really am all for getting your feet wet - but investing in something you don't have your heart in could turn out bad, especially if you're not prepared for it. All of the BEST equipment in the world is meaningless unless you know how to use it. All of the music in the world is meaningless unless you can figure out what it takes to move that particular crowd on that particular night in that particular mood. Believe it or not, they don't want to dance all the time.
From what I have read - I really think you should spend some time with the DJ's (in various venues) vs watching / talking to the DJ's (at weddings). Like I said, things are quite different in the shoes of a DJ vs a Videographer. I don't believe you should attempt this business without hanging with some experienced guys. Attempting this without the experience could have very bad consequences, for your DJ and Videography world.
Hanging with DJ's costs you nothing other than time and personal investment. You get to see different equipment, different styles, etc. Depending on the DJ (and venue), he / she may even let you run the controls for a bit. This would be the perfect avenue to see if this is something you want to take further. Let me take this further by saying that a 'One time outing' is not enough to figure this out.
I said $4000... well that is what I think is enough to buy basic quality gear for events up to about 200 people. I'm not including cables, mics, music, BACKUP gear, and computers...... as you will likely want a backup computer unless you have some other backup plan.
I agree here too. Whole heartedly.
Do your due diligence, create at least a bare minimum business plan, and then ask yourself if you really want to DJ.....
I agree here too. If your heart (and mind) is not in it, you will be wasting your time. Contrary to what some believe, this is not a way to quick cash.
I am in no way trying to discourage you. I'm really trying to open your mind to angles you might not have taken into consideration. There are yet other angles not even discussed in here. There's more to it (the business) than just equipment and music.
Try to understand it being similar to me saying I want to be a videographer, so what camera should I buy? Knowing as little as I know about videography (and I have been told I do take good pictures / movies), I'm sure there's alot more to it than that. I'm also certain that you would agree that a wedding should not be my starting point, and that I should have a plan of attack for this venture. I probably also need to identify how much I'm willing to put into this venture (among other info) - which helps you tell me where I could probably fall and how I could best use it.