Sony's BVM-X300, a 30" 4K (4096x2160) reference monitor is Sony's flagship professional monitor. It features a high dynamic range, wide viewing angles, quick response and high contrast. The BMV-X300 can display 4K, 2K, UHD and HD formats and supports wide color gamut standards.
The BVM-X300 will ship in February 2015, price is not yet determined.
OLED type:
30" 4K AMOLED panel
Although this monitor costs a lot of money and may not be described as reasonable by many consumers, I find it a great step forward greatness in consumer-grade monitors.