Each pet in Pet Simulator X possesses a unique value within the Roblox experience. You must be aware of the values so that you can ideally complete a trade. You can find a list of values by searching on various websites available online. I personally use sites such as "Petsimxvalues.com" to gather this information. With access to the Trading Value List, you can make better decisions about what price or which pet you would like to trade your pets for. Nonetheless, I would want to specify that the prices aren't stable and change from time-to-time.