Empowering GR10 costs 560,000 gold.
Empowering GR20 costs 2,280,000 gold.
Empowering GR30 costs 5,800,000 gold.
Empowering GR40 costs 9,500,000 gold.
Empowering GR50 costs 15,600,000 gold.
Empowering GR60 costs 25,400,000 gold.
Empowering GR70 costs 34,100,000 gold.
Empowering GR80 costs 45,800,000 gold.
Empowering GR90 costs 61,000,000 gold.
Empowering GR100 costs 82,000,000 gold.
Empowering GR110 costs 111,000,000 gold.
Empowering GR120 costs 149,000,000 gold.
Empowering GR130 costs 201,000,000 gold.
I don’t know the values for GR140 / GR150, as I’ve never gotten that high but, as you can easily see, the gold cost to empower GRs rises steeply the higher the GRs you’re doing. Whilst you get approximately two thirds of the empowerment cost back on completion, you still have to factor in paying one third of the empowerment cost per GR if you want the extra gem upgrade rolls.
If you assume that you get 4-5 GR keys per T16 rift (3 guaranteed, 50% of 4th, follower emanating the set that can generate extra keys) then, on average, from 10 T16 rifts you’d have 40-50 keys so let’s say 45 keys.
If you wanted to empower 45 GR130s, that would cost you…
45 * 201,000,000 gold = 9,045,000,000 gold.
Two thirds of that will be returned on completion of each GR which is a rebate of…
(9,045,000,000 / 3) * 2 gold = 6,030,000,000 gold.
Which means the net cost for running 45 empowered GR130s would be…
9,045,000,000 - 6,030,000,000 gold = 3,015,000,000 gold.
Okay, so to fund that purely from gold obtained by running the T16 rifts that generate the keys, each of the T16 runs would need to generate…
3,015,000,000 / 45 gold = 67,000,000 gold.
Without some significant +Gold Find, you’re not going to be earning 67 million gold per T16 run.