I did this for around 2 years, finished in febuary. Basically the stuff you'll need is
computer, amp, mixer, lights, speakers and all the cables and stuff to go with it. I suppose you could probably get all this for around a grand.
We had around 2 or 3 "units" out per night which meant atleast 4 sets of equipment (incase anything failed) and we worked off computers, which were good for the most part, in the 2 years i was doing it i only ever had about 5 problems but we always got round them.
Also if you're doing it on a computer you will need a vast collection of mp3's, we had around 20,000 songs, didnt use all of them but we were able to play a lot of the more obscure requests since we had them
Weddings are fairly easy and generic but you wont make much money from just doing weddings, also have a look at any competition and who else are doing the same sort of thing in the area, see how much they are charging and stuff, it seems to take a while to build up a reputation if you're not the only one doing it.
edit : ohhh and we used pcdj red, works pretty well i found
