I did recently, but I got it installed at Best Buy so unfortunately I can't help you with the DIY part. But wiring kits start at around 110$, depending on brand and gauge.
One thing I can suggest: if you're going for alot of watts, I hope you're putting a capacitator (I think that's what it's called) in. I'm gonna have to do that this week, I dreamt that my alternator died on me last night. :\
Where do you plan on mounting your amp? And what kind of box will you be using?