Yes, the first Televisions that support 4K resolution are available in stores. But the prices are very high. The first models had a price of more than 20.000 Dollar. But now it will be more and more 4K TVs available for around 5000 Dollar. You can find the Sony XBR-55X900A for 4998 Dollars, the LG 55LA9700 for 5999 Dollars and the Samsung UN55F9000 for 5498 Dollars. And you can also find very cheap Seiki SE50UY04 TV from China for 1130 Dollars but the quality is very low and it is not recommend to buy this TV.
At the moment there are only a few Blu-rays in 4K resolution available. And Sony released a Media Player with 4K movies but the Media Player works only with Sony 4K TV. Look at the article about 4K Blu-rays for available movies.
Buy 4K TVs here:
Sony XBR-55X900A 55-Inch 4K Ultra HD 120Hz 3D LED UHDTV
Samsung UN55F9000 55-Inch 4K Ultra HD 120Hz 3D Smart LED TV
LG Electronics 55LA9700 55-Inch 4K Ultra HD 240Hz 3D Smart LED TV
Toshiba 58L9300U 58-Inch 4k UltraHD 240Hz 3D Smart LED HDTV (Black with gun metal trim)
Seiki Digital SE50UY04 50-Inch 4K UHD 120Hz LED HDTV