Whether you're a professional or just starting your career, it's extremely important to use high-quality DJ equipment. So, let's get straight to the point. DJ headphones are one of the most essential pieces of the kit, since you'll need them regardless of the configuration you have. Configuring a controller may be more expensive initially, but it will help you save costs in the long run.
In fact, if you're able to mix proficiently in basic decks, you'll notice a sudden jump in your skills when you switch to a professional team.