First post so please have mercy. Costco has the Samsung 55" 4K UHD Smart LED LCD TV on sale for $850 but also offer a $70 manufacturer discount which comes out to $780 for members. The next cheapest price is $900 at BestBuy. I believe this model is the same as the KU6300 55" model just listed different for Costco inventory.
I would also recommend getting the squaretrade warranty as well. This deal is available not only online but also in store.
For reference, I was one of the individuals who purchased the 65" Panasonic cx400u 4K TV at Fry's Electronics and the upscaling was terrible so I returned it. Visited my local Costco (Tempe AZ) and was able to pick up this TV, much better quality TV compared to the Panny.
Here are the reviews on rtings: http://www.rtings.com/tv/reviews/samsung/ku6300
Some important notes:
1080p @ 60Hz @ 4:4:4 --YES
1080p @ 120Hz--NO
4k @ 30Hz @ 4:4:4--YES
4k @ 60Hz--YES
4k @ 60Hz @ 4:4:4--YES
"Almost all the resolutions that we have tested are supported on this TV, the only exception was 1080p@120Hz, but that was to be expected for a Samsung TV. For sharper text 4:4:4 you must set the input type to 'PC'. For 4K@60Hz@4:4:4 you must enable UHD mode."
HDMI: 3 sources
USB: 2 sources
5.1 Passthrough ARC Dolby Digital--YES
5.1 Passthrough ARC DTS--YES
5.1 Passthrough Optical Dolby Digital--YES
5.1 Passthrough Optical DTS--YES
HDMI 2.0 Full Bandwith--YES
ARC : YES (HDMI 3)
USB 3 : NO
HDCP 2.2 : YES
CEC : YES
MHL : NO
Variable Analog Audio Out : NO