Board Thread:Questions and Answers/@comment-116.15.138.253-20150616152553/@comment-25889587-20150616160658

Pet sales is like a wager. If you really think that you will not get the pet that you want from the Extra Rare Egg more than 5 times, it's a better choice to use the Pet Sale.

But I don't recommend it though. It's still better to get 5 pet that you don't want than 1 pet that you wanted, since the more pet you have, the more chance you are going to get the pet that you wanted in the long-term.