I don't want to be a pain, or put you down, but you should give it some thought. I mean, a lot of people think it's fun to mix, play at clubs, and create live sets. In fact, it involves a lot of effort and time. And it can get very expansive. A lot of people that I have met before would simply get fired up about becoming a DJ, and about the music, but drop it after about six months. I'm not saying that you will, I'm just saying that you should consider it. I'd personally suggest that you try software mixing, and if you know some friends with equipment, ask them to give some lessons. Try it on their equipment (if they let you) and see for yourself if you REALLY like it.
If you do, you have a variety of different options to choose from for equipment. Each style is different, it has it's own cons and pros. You need to find which style appeals to you more. There's digital mixing, there's turntables, CD decks, and even a mix between hardware and software. The best way to approach it is to play around with every style for a bit and determine which one you like more.
I started with software mixing a couple years back. I liked it at first, but the more I got into the music, and the more I learned about the art of DJ'ing, I moved away from it. Around that time, my other buddy got some low-end equipment, and I got to play around with his belt-driven Stanton's. Yes, you heard me right.
(Man, the number of times he replaced those belts...) Anyways, then as the time passed, he got better equipment, and I got to play around with it. So I got a taste of what I like and what I don't.
I personally found that I liked a mix between hardware and software. I find that vinyls get too expansive these days. And keeping up with the latest tunes could get ugly; you'd develop the "black crack" addiction. My buddy shelled out more than $1,500.00 for his vinyls, which is probably around how much his equipment cost all together, and he got through some channels. (with large discounts.) This is why I am leaning towards: Final Scratch 2.0. Google it. Although I've gotten some mixed reports about it. Anyways! In short, to answer your question, play around with software, try out mixing with turntables, CD decks, or whatever. Once you get a taste of what you like, by then you will know what you'd need to obtain to be able to DJ.
EDIT: Although, if you feel the passion burning within you to spin, listen to what DreaMension has said. Get some second hand equipment from ebay.
... Because lets face it...watching your favourite DJ mix it up in Abelton Live, is about as exciting as watching someone check their email. ...
I couldn't agree any less.