Ok, since test realm is up and I had free crowns to play with, I decided to see what was a more efficient way to obtain gold with crowns. Which I wouldn't do myself since gold is super easy to come by in this game, but I have seen people asking about it. 800 crowns = 1000 gold. That is 1.25 gold per crown. Not a lot. You get a slightly better deal on larger amounts of gold, but not enough to overturn my findings.
So I bought 10 packs each of several cards and sold everything I possibly could, and totaled up my gold income -vs- crowns expediture.
10 Dragons Hoard card packs Cost 3990 crows. Gold obtained 12,488. Gain of 3.12 gold per crown. and 1 unsellable gardening treasure card 249% of the value of buying gold.
10 Hand of Doom card packs Cost 1580 Crowns Gold obtained 5690 Gain of 3.6 gold per crown and 11 unsellable Boss Minion treasure cards. 288% of the value of buying gold.
10 Eye of Bartleby card packs Cost 1150 Crowns Gold obtained 5709 Gain of 4.96 gold per crown no unsellables 396% of the value of buying gold.
10 Snack Pack card packs (regular, not mega) Cost 1150 Crowns Gold Obtained 11,438 Gain of 9.94 gold per crown no unsellables 795% of the value of buying gold.
Now I am not swearing on my math, I did not double check everything, my hand was already tired from writing it all down, but as you can see, if you really have crowns to waste and can't wait to get your gold by fighting, selling snacks is a far better option than just buying gold with crowns.