My suggestion is to change the rarity of the zerda breed change item (and consequently, the breed itself) from uncommon to rare.
Currently the gap between a common breed change item (100k pebbles) and an uncommon breed change item (150 moonstones = ~1,5 MILLION pebbles) is HUGE, while the gap between an uncommon breed change item and an epic (two ”rarity levels” higher) breed change item is only 50 ms (volmyr 200 ms). Meaning a future rare breed change item would probably be priced at ~175 ms.
These price steps feel quite uneven. My solution would be to change the rarity of the zerda breed change item to rare and keep the price at 150 ms. A future uncommon breed change item could be priced 100 ms, or even better, pebbles.
Also, ~$15 USD for an uncommon breed (only the 2nd of 5 rarity levels) is quite a lot, I think that pricing would be more suitable for a rare breed.
Thank you for reading!