No iOS. Android only. You can just look at Amazon Coins on their website. There is pretty much always at least a 15% discount on 5000 coins and 10% on 2000 coins: https://www.amazon.com/dp/B0096E8EC2 1 coin = $1 in-game.

They already have a coin

https://www.amazon.com/Amazon-5-000-Coins/dp/B0096E8EC2

It isn't just the app store and you don't need a Promo code. It is on the website as well. So basically:

• 5,000 Amazon Coins
• List Price: $50.00
• Price: $39.50
• You Save: $10.50 (21%)

And 50,000 ($500) is 30% off too by the way. And 2500 ($25) is 18% off too which isn't too bad.

You can buy 5000 coins for $42.50. The cost in-game will be the the cents conversion USD to coins (4750 I think).

https://www.amazon.com/dp/B0096E8EC2

Then you announce your own coin. You take no.1 spot in a matter of weeks.

Amazon has had a coin for years yet few have noticed.

Also, if you buy 10,000 coins at once, you pay only $80.

So, if I understand OP correctly, you pay $80 for 10,000 coins, get 80 packs and 5000 coins back, so a total of 120 packs for $80 (compared to $70 for 60 packs if you buy from Blizzard.