There are a few you can actually buy now and about 10 or more by the end of the year. For now, you just have the Sony/LG/Toshiba 84" 4K LCD all using LG Display IPS 84" 4K panel. Price range from around $15,000 - $22,000. A lot of that price is sheer size than the 4K tech. Samsung has 85" 4K for $30,000. Seiki has a 50" 4K for $1300. Sharp and Toshiba have a few 4K but they are over in Japan.
Now for a few that should be available by the end of the year. LG has a 55" and 65" coming around for around $4-5K. Sony also 55"-65" 4K using AUO panel at probably slightly higher $5-6.5K. Hisense will have a few also. They will probably have the cheapest 65" 4K at around $3500. Next year you should see more manufactures offer 4K and prices to fall rather quickly. Especially since the PS4 with 4K playback will be out by end of the year.