ok, using a laptop, that would be personal preference, you still have to choose for urself cd or vinyl, they have time encoded vinyl records and time encoded cd's, so serato seems the way to go, now its up to you
2 techninc 1200's mlk2- about 500-600 a piece
2 denon s3500's- about 500-600 a piece, these are a real gem, they have direct drive motors and spin like real tables, you will have a lot of opions with these ,and plus since ur doing the wedding type gig, they would work out for you, so many people at shows like these will bring u a cd to play, and you'll be ready, since u have like $3,000, you might need a little more scrilla
invest, and i stress the word invest cuz this is an investment to a ligitimate bussiness, buy some good powered monitor and like 15 or 18 inch sub box, this is very important cuz your sound quality realy matters,