BCD 3000 is a really nice way to start off learning to mix. it usually comes bundled with Traktor LE so you'll get all the basics (2 decks, a bunch of effects, 4 beat looping etc). While you can't do anything super fancy on it, it will teach you all the basics until you're ready to sell it and move up a notch. Also it has a built in soundcard which is nice

Otherwise I would recomend the Numark Total control. About double the price but a much nicer unit (nicer knobs, better quality jogs, more buttons, better placed leds etc)