Before you get your hopes up... remember the 470. Initially it was like £10 cheaper than a 480, and some (looking at you, Asus) 470s were more expensive than 480s
You really shouldn't expect anything "for free" these days. If it performs like a 64 don't expect it to be £100 cheaper
thew 470 cost more because of the mining scandal i remember it was cheaper then 480 for awhile evenn on launch till the mining fiasco
benchmarks etc show the vega 56 a really good card