I would like to clarify a few points. Let's start with level 1 and a Fortress. Then the minimum costs are as follows:
horses + angels = 45 gold + 15 crystals + 12 potions + 12 runes + 12 scrolls + 12 crystals + 25,000
unicorns + green dragons = 25 gold + 40 crystals + 14 scrolls + 34 crystals + 23,000
Even the Rampart is cheaper, although elves are considered, but griffins are not.

paladins + archers = 55 gold + 15 crystals + 22 potions + 22 runes + 22 scrolls + 22 crystals + 48,000
warriors + gold dragons = 30 gold + 75 crystals + 25 scrolls + 60 crystals + 47,000
There is a strong bias towards one resource (but there is a warehouse), and the Rampart has become more expensive, but only because its guild is already level 3, while the Castle is still at level 1.