I've noticed after changing the colour of a couple of pets, the forest alchemist is not taking any silver for its services.

I just changed this lykos color succesfully (http://beastkeeper.com/pet/429384) and still have the same amount of silver on my account. I don't know if it is the same problem with the 10 items required.

I know it is kinda a nice glitch, but still....

Thank you for reporting. It seems that Forest Alchemist feels generous :) We'll fix this issue soon.