If you were building a beginner setup from scratch today, what would you buy first? The goal is "something enjoyable that won’t induce despair by Tuesday". 

I know a little bit about DJing, first thing would have to be a laptop, even a cheap old underpowered one should get you into the basics (and you can try your hand at producing), but, having said that my first instincts were actually a very basic 2 channel mixer. 

Unfortunately, the mixer is useless without the PC, not the other way around, but you're not really going to learn anything until you start using a mixer (and really one without lights and then vinyl turntables and actual beatmatching, but that's just me being a purist (or at least pretending)).

What about other parts of music? How high are the barriers to entry, really?

---