crowns vs subscription through math

Well, i decided to discover what is cheaper, crowns or a full subscription

$10 buys 5000 crowns and that will finish up all of WC.
KT costs more so $10 gets you through the pyramid of the sun and the commons, then you need $10 more to finish the krokosphinx and to buy the inside of the temple of storms. then another $10 you finish kt
That's $40 to finish KT and WC.

Another $10 gets the MB commons and finishes all of Digmore station and Newgate prison
Then $10 more finishes MB and gets the MS commons, then it gets expensive.
$10 gets the Hametsu Village and the Crimson Fields and Tataki outpost.
Then $10 more gets you the Shoshun Village, Kishebi Village and the watery place, (I forgot its name) Then another $10 gets the Shirataki Temple and the temple place and the Ancient Burial Grounds. Then Another $10 gets the Village of Sorrow and the tree of life and Basilica.
That's $60 to finish MS and MB.

Then $10 gets the Atheneum and the Tower Archives. Another $10 gets the Grand Chasm and the Plaza of Conquests. Another $10 gets Past and the Necropolis. Another $10 gets the crucible and Drake Hatchery. $10 more gets the labyrinth and the DS academy. Then $10 more gets you the Crystal Grove and the Forum. Then $10 more gets the dragons roost and malistares dungeon.
That's $70 to finish DS.

That adds up to $170 to finish the game with crowns, vs. a full year subscription of $60 or $80 if there's no sale. THE SUBSCRIPTION WINS!

So getting a subscription is cheaper than buying every area with crowns!