if you want to get into djing start with virtualdj (
VIRTUAL DJ SOFTWARE - MP3 Mixing Software) and play with that for a few months. if you think its something you want to continue doing swallow your pride and cough up $500-800 for a real dj system.
dj equip isnt cheap, buying cheap off brand dj equipment will be like buying a bb gun and expecting a real gun. i made that mistake and i am still financially paying for it. get a real dj setup (technics sl1200s and pioneer cdj800s are the industry standard, you can get away just fine with cdj400s.)