CDJ 400s are a good shout, they're not too expensive if you grab them secondhand off gumtree or ebay. They have usb functionality although they're fairly old so you can't use too many tracks to one drive. they have really cool Jog wheel effects which are fun to play about with too. Next best thing is to go for CDJ 350s or 850s, just keep an eye out on ebay for a good bargain