[These are just some fictional statistics that I created with a help of 'Professor Google'. Cause the amount of money never mentioned in any of the episodes.
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[Tourney Winning Prices]
The prizes are forty thousand gold dragons for the winner of the joust, twenty thousand dragons for the runner-up of the joust, twenty thousand dragons to the winner of the melee, and ten thousand dragons to the winner of the archery contest.
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House Lannister (Tywin) - 12 million Golden Dragons [3 million Gold Dragons loaned to the crown, 1 million Gold Dragons loans and various investments, 2 million Gold Dragons in reserves, 5 million Golden dragon in Gold mines, lands, harbors & property and 1 million Gold Dragons of taxes from Wester lands liege lords] Total 12 million Golden Dragons]
House Tyrell - 5.82 million Golden Dragons [The Reach = 4x Duchy of Cornwall about 1.45 million Gold Dragon taxes each year.
Daenerys Targaryen - 4.45 million Golden Dragons. [Young Dragon each 113,520 Golden Dragons. Total 340,560 Golden Dragons and 8,600 unsullied 113,520. Roughly 13.2 Golden Dragons for each unsullied and 4 million from masters treasury after what was left, after some expenses. ]
House Tully - 800,000 Golden Dragons
Petyr Baelish - 700,000 Golden Dragons
House Frey - 550,000 Golden Dragons [Mainly from taxes from Merchant and Lords who cross the twins]
House Martel - 500,000 Golden Dragons
House Arryn - 460,000 Golden Dragons
King Robot Baratheon - 400,000 Golden Dragons [With an extra of 3 million loan from Lannister and 3 million loan from Iron Bank. All were spent on King Robert pleasures]
House Greyjoy - 340,000 Golden Dragons.
House Stark - 300,000 Golden Dragons.