....please define "playing"? like...learn mixing tracks?you can spend whatever/howmuch you want... if you want some basic functionality of DJ'ing, tempo sliders knobs adjustment wheels etc look at the Vestax VCI-100 it's what I use /shrug. It comes with Traktor which is pretty nice if i do say so myself.
Once you have bought your software license (cubase is great), you can download a copy from a torrent site in case you lose the CD. That's probably the best thing for a beginner to do It's easily available. Never ever download it if you havn't paid for it though - its illegal and immoral. Oh and don't upload it to other people. Think I covered everything.