Then I'll recommend buying a more universal system that can play Cd?????????s/DVD?????????s and be hooked up as a midi controller as well. It's not that I don't like the PC concept, it's just that you?????????ll need to be able to DJ on multiple platforms before you?????????ll ever get recommended doing club gigs. Many and I mean many places doesn't allow you to plug in all your poop on their PA system not to mention wasting 30 minutes of your 1 hour set putting it up and taking it down. It's such a waste really that I started leaving my stuff at home for any party as long as there at least is something we can mix on.
Cheaper cdj?????????s doesn't have the Sync function as it requires some computer power to run the beat grid formula. Calculating the BPM however is a given on CDJ?????????s but remember it's not that accurate and can cause a track to drift over time but it won't sync your tracks perfectly for you. You?????????ll have to get your phrase lined up and play with what works the best for you. Easiest method to practice IMO is by trying out 2 minimal house songs, Cue right before beat 1 on the incoming deck, line it up on any beat IWO just beat match and don't think about the phrase, listen to how long it takes to drift (16 bars should be fine). Now you have the BPM set correctly, Hit the play button repeatedly on the Beat of the song and just release when both decks are on Beat 1. You?????????ll need to practice this method over and over until you dream about it and then some more. Know your songs well cause visually looking at a wave file gives out a lot of information regarding the breakdowns etc????????? Many songs like to deviate and have a 1 or ????????? a bar section followed by immediately beginning with the phrase that will through your other deck off.
Maybe look at something like this:
http://www.numark.com/mixdeckquad
I actually have the 2 channel version of this thing and for the price it's really flexible. I'll recommend trying it out.
Also for extreme mobility check out the Vestax Vci 300 or Vestax typhoon. Both units fit in a laptop bag and doesn't even need a power adapter. If your laptop is plugged in, the USB port should power the whole thing. But like I said try out the Mixdeck first.