Start: 600 coins + Collection: 600 coins every 8 hours = 6000 coins in total.
Plus additional coins from quest and freebies.
For collectingtimes check this.
New dragon: Nyami, buying out the last piece is 1500 coins.
We also can get 250 gems from a treasure chest.
We can also get other rewards for collecting pearls on our way.
There are 34 purple tiles which could hold the chest with the 250 gems. It is not located in a special place. It is just about the number of chests you have to open to get that reward. For some players it is number three, for some number 34. I drawed the cheapest way to open all chests on purple fields. If you are unlucky and have to open all chests on purple fields to get the 250 gems you will need around 8200 coins. Mobile and Windows 10 users should skip the tutorial .
The chests contain:
Orange fields: Orbs of Aquamarine #206,
Green fields: Orbs of Double Sea #279,
Purple fields: Orbs of Kraken #516, 250 gems.
Not coloured fields: Orbs of Aquaking #732, shells. Collect pearls to get Nessy #521 and a chest with tokens, joker orbs, essences and food.
All chests can also hold gold, food and essences.
Not each chest holds dragon orbs.
Map 1 is for mobile and windows 10 (7960 coins), map 2 is for browser version (8190 coins).
Happy treasure hunt.