pioneer cdj1000s are good if you can find them in your budget as they will play mp3s and can be set up to be very similar to vinyl mixing [just can take a while to get it perfect for you]

if you do go for a laptop get a pro audio soundcard and if its not adequately shielded [rigs can generate proper big magnetic fields] then wrap the soundcard and the laptop in aluminium foil to reduce inteference [yes it may look silly but it does work ]