Disagree with this, Elm is 70 demon crystals per copy. During the daily boost week where the 70/8 map has 100% chance drop demon crystals, 21 demon crystals costs 8 stamina. 70 / (21/8) = 26 2/3 hours per copy of Elm. You need 8 copies of Elm on average to min cost her (first copy, 1 @100% CR chance, 2 @50% CR chance, 4 @25% CR chance), so that's a total of 213 1/3 hours of natural regen to min cost her.
Contrast this with Chloe, who has no 100% drop map sadly, so is 14 hours per copy (assuming the 7 stamina map is 50% drop chance). She needs 16 copies on average to min cost (original copy, 1 @100%, 2 @50%, 12 @25%) so 16 x 14 = 224 hours to min cost her.
HOWEVER, note above Elm figures were at 100% drop rate for demon crystals, which we obviously don't always have. Outside of boosted daily drop rates it's probably more like 70% drop rate, which works out to be about 300 hours to min cost her.
So normally Chloe is actually quite a bit cheaper than Elm simply because of how much less investment it is to get copies of her, despite needing CR -5 vs CR -3. The only issue is you can farm demon crystals twice a week, vs being able to farm Chloe only 1 day every 1 1/2 months or whatever.
Special bonus: Fewer rainbow faeries are needed to raise Chloe's skill since you need 16 copies of her anyway for CRing vs 8 for Elm. And the 7 stam Chloe map drops platinum armours to assist with levelling her.
I now look back on the days when I use fairies-bronze to conserve cans. #TinCanWorldproblem
