Upload & Sell: Off
Posted on another thread about this, but I just got the Dell UP2414Q monitor (4k 24") -- works with MBP/Retina via thunderbolt->display port and HDMI. Resolution detected correctly. but no scaling (unlike the laptop's retina display). Update coming in 10.9.3 to address external 4K monitor scaling apparently.
Great monitor though. A pair of those would be a good bit less than the 32" Dell UHD display and you could drive both with MBP.
You can scaling in the meantime before 10.9.3 if you follow the later steps in my post about getting mac mini to work with UP2414Q. Have to use SwitchResX to create a custom 51260x2160 mode and in the end you'll find a 1920x1080 HiDPI mode in SwitchResX and pick that (don't worry, it's 5120x2160 not 1920x1080, but it makes the text and icons the same physical size as if it was a 1920x1080 screen).