Maze explanation is here.
Startbonus: 400 coins
Collections: 600 coins every 8 hours (7200) = 7600 coins.
The total does not include coins we can get from quests or dragon tv.
For Collecting times check this.
Dragons:
Octopus -R- #154: The path costs 860 coins.
Vibrant -VR- #1053: The path costs 2825 coins + 1 key = 3285 coins.
Icewind -E- #611: The path costs 3630 coins + 2 keys = 6005 coins.
Psybolt -L- #1533 or Geoforce -L- #1532: The path costs 6020 coins + 3 keys = 10830 coins.
Timelimited:
11-13: Deluge -L- #1358: The path costs 8165 coins.
12-13:- White Princess -L- #1441: The path costs 6720 coins.
