I bought the 2nd fountain, the sheep (regret, didn't need), spent about 150-200 gems in total - 30 making armor for the fawns from being too low level, about 50 from rushing the garden for 2 gems to spawn another donkey, and the rest rushing various things. I also bought the $5 10 minute infinite energy 3 times to grind most of those donkeys
I'm fine with that gem cost for the armor, as the fawns are absolutely worth it. At my level 700 coins each that frequently is really good even before their drops. The rewards are fantastic for me and I'm happy with it all. I won't spend this much in the future, but there was the bonus fun of posting first results