I did find some motherboards that support DDR4 for around $400, along with a crapton of other cool features (but who needs 2 ethernet ports?). I put together a theoretical build and the price of a nice liquid-cooled case with mobo and RAM is $1200. This is before the CPU, graphics card, hard drives, or power supply. It's probably still not worth it, but I'll wait and see what the situation is in in 4 or so months.
PC building is exciting!
This is also the first time that I'm taking into account the color of the components. It's going to look sweet.
EDIT: "Worth it" is misleading though. I'm waaaay past the 'because I can' point by now.