Anyway, topiaries are pretty fast and I was hoping the dragon might be pretty valuable as a masterpiece.
Lucky for you, you have me! I had my Sculptor churn out some "topes" for you. He does have all the sculpting challenges complete (except for the ice one) and has the Artisan Crafter.
Dragon Dougherty: Masterpiece x1 = $2,647. Brilliant x2 = $1,456 and $1,472. Good were between $756 and $955. I also had one nice but its head had been chopped off, worth $931.
The topiaries I had left on my lot were: Penguinopoly, Brilliant worth $1,323; Anna the Panda, Brilliants worth $1,132 and $1,334; and Felix the Giraffe without a head, Brilliant worth $1,315.
I am not sure if the lack of head raises the value or lowers it. If nice is less valuable than good, then according to the above about the Dragon, lopping off your creations' heads is a great idea. This is a random occurrence, in case you haven't seen it. You just receive a notice that things didn't go according to plan. You have to View the item in order to see its grade and value.