I bought an open box TV once. It came without the instructions, remote, 3D glasses, and network dongle, but it was 10" bigger than what I had planned to buy for not much more money. It lasted me about six years before it finally failed. I don't recommend buying a 65" TV unless you have a vehicle large enough to comfortably move it. My new TV is just a tad smaller, and the store hauled away the 110 lb paperweight for a small fee.
I have had success with refurbished cameras, keyboards, mice, and other electronics.