Mixer

• A mixer allows you to manipulate volume and fade in and out of the media source(s) you plug into it. It also lets you cue up through headphones the tracks you plan to play through your speakers, before the audience hears them.
  
  

Media Players

• Turntables, CD/MP3 players, iPods and computers can all adequately play your music collection. Though largely a matter of preference, each provides similar features that permit you to manipulate tracks differently.
  
  

Amplifiers

• Amps (or receivers) project the sound produced by your media players. The more powerful the amp, the more robust the tone and greater the range. Quality can vary based on how the amplifier deals with interference and overheating.
  
  

Speakers

• Most DJs need four speakers, a right and a left, each with a tweeter for high notes and a cone for low notes. Cost depends greatly on how much power they can handle and the ruggedness of the housing that protects them.
  
  

Microphones

• Mics can be corded or wireless. Mobile DJs may need a wireless mic to address the crowd from anywhere in the room. These can get expensive, largely because of the need to eliminate interference and feedback, which will be your greatest concern.