GPD / Treasure Dragons: There is 14 of them, 10 removed 2017-02-14, 4 still left in game
2017-04-18 to 2017-04-25 Alchemy, 4000 gold, on sale for 2400 gold
2016-10-14 to ? Gold Horizon, bingo tickets or 4000 Gold.
2016-06-03 to 2016-06-10 Kintsugi, 1600 gold, sale 800 gold
2015-12-11 to 2015-12-18 Northstar, 1600 gold, sale 640 gold
2015-09-22 to 2015-09-29 White Gold, 1500 gold, sale 600 gold
2015-05-29 to 2015-06-02 Rose gold, 1600 gold, sale 600 gold
2015-02-21 to 2015-02-28 Forbidden, 1600 gold, sale 600 gold
2014-12-19 to 2014-12-26 Sterling Silver, 1600 gold, sale 600 gold
2014-07-18 to 2014-07-25 GoldLeaf, 800 gold sale
2013-12-31 to 2014-01-07 Gilded, 2000 gold, sale 300 gold
2013-09-27 to 2013-10-02 Goldwing, 1800 gold, no sale?
2013-07-16 Midas, sale 800 gold
2013-06-20 Stainglass, sale 800 gold
2013-04-27 Treasure, sale 800 gold
Other sales (feel free to update list):
2016-06-14 to 2016-06-21 Stainglass and Midas on sale for 400 gold
2016 - no GPD sale for Cyber Monday
2015-11-30 to 2015-12-01 Cyber Monday - all GPD dragons for 800 gold
2014-12-01 Cyber monday, all GPD for 600 gold
So, if you started playing in 2013 - good for you, you could buy some/all GPDs. If you started 2015 (like me, 3rd quarter) - you'll be lucky with one/two, and if you started 2016... what a bad luck...
Bring back GPDs and put them on sale - give this game "touch" again!