What is a good price to breed my sylestia to users

That depends highly on the pet youre trying to put up for breed. Honestly? Unless its a themed, 6vis, high in stats, has difficult to obtain genes, or is just plain rare, you probably wont be able to get much at all for them. I highly recommend checking the Advanced Search for breedable pets that are similar to yours. That should give you an idea of what theyre worth,