Cost of evolving a 6 stars ally

Using largely found 3 star angels to upgrade 4 star angels from event dungeons

The cost of evolving a 6 stars ally is as follows :

With a 5 star angel (50% chance to evolve)
Material : 2*4 star angels + 20*3 star angels for one 5 stars angel

65600 gold to obtain a +5 4 stars angels

Total is 145200 gold to obtain a 5 star angel

Considering a cost of 50000 gold to evolve with 50% chance :

145200*2+50000*2 = 390400 gold

With a 6 star angel (100% chance to evolve)
166000 gold to obtain a +5 5 stars angels

Total is 350000 gold to enchance 5 stars to a 6 star angel

Considering the use of 3 star angels to upgrade 4 stars into 2 5 stars into a 6 stars.

350000 (2 5 star angels evolved) + 145200*2 (4 4 star angels evolved) + 50000 = 690400 gold