The very best 75-inch TVs can vary wildly in price. The LG G3, for example, will run you an eye-watering $3,500 / £2,770 (around AU$5,400), while Hisense present a much more affordable option in the U8K at $1,300 (around £1,000 / AU$2,000).
The difference in price here seems drastic considering both examples offer excellent picture quality. It all depends on how much you're willing to pay for extra bells and whistles and design sensibilities, such as the G3's wonderfully thin design and best-in-class options for gaming.
Do be extra wary about TV sales that sound too good to be true, though. If you see a 75-inch 4K TV for around $600 / £600, it's probably going to let you down in terms of picture performance with bad backlighting and cheap edge-lit LED panels that produce poor black levels and contrast.