I figured I would throw in my 2 cents. I am not a DJ, but my job puts me in daily contact with both "superstar" and bedroom DJs alike, so I can at least relay their advice.

If you think you want to DJ, get a cheap pair of Numark or Gemini decks first, just to see if you can do it, and have the patience to do so. If you find yourself getting bored with it, or just can't seem to do it, don't go any further and get a pair of 1200s and a decent mixer.

If you manage to stick with it, get some 1200s secondhand, if they're well taken care of, they'll be good as new. That way you can blow more money on a good cartridge like the Ortofon Concorde, (called such due to it's resemblance to the airliner), or one of the Shure models. A good mixer is a must, you can use it for years later..don't get a low-end mixer and expect to make money off of it, it will more than likely break during your first party or event. Invest in something like the Pioneer DJM-600 or the Rane 2016. Six grand'll get ya an Allen and Heath Xone:V6 tube mixer, the current gold standard! That one's more of an install mixer, I just listed it for factual reasons.

As far as amps and speakers, rent until you can get some cash together for a good, solid system. Don't go with the self-powered cabinets like the JBL EON series, the sound quality is mediocre at best. Go with 2 nice amps, Crown K2, or QSC Powerlight series, and get some decent EAW or standalone JBL cabinets. If you're scrounging for change, just get the full-range cabinets and invest in subwoofers later on.

As far as getting gigs, start out the obvious way. Do house parties and such, but try not to compromise your style. You want people to hire you as being a house/trance/breaks/whatever DJ, not a human jukebox. Record demo CDs, and pass them out at clubs, festivals, try to leave a few in the flyer section of your local vinyl outlet. Send them out to booking agents, promoters, and regional clubs as well. Go to the Winter Music Conference in Miami, pass them out to everyone! People love free stuff. Post mixes online wherever you can, from dance music oriented chatrooms, to club message boards, and DJ forums. If you're good, you'll get booked at some point.

Good luck!