Ask HN: Cheap way to drive 2x 4K displays?

I bought 2 4K displays on Black Friday to replace my existing 1080p displays.

My current card doesn't support 4K. However, even the really expensive cards only have one displayport output. I don't do much gaming on this machine and just use it for work (web apps development etc), however I don't want absolutely terrible 3D performance.

Any recommendations of a way to get both monitors driven at 60Hz? I can see options for doing it at 30Hz but not both at 60Hz. I'm surprised this is such a complicated thing to do considering 4K displays are so cheap now.