I know somebody asked a few sim weeks if having made many ice sculptures done would increase the value of those sculptures. I now am fairly sure that how many you have made does increase the value of them.
I first noticed a big jump in how much ordinary, brilliant and masterpieces were worth when I was sculpting gen 4 and 5 and was having some issues getting the quality of sculpture that I wanted. I had made lots and lots of sculptures of each so I was a bit unsure if the jump in value was because of that or the number of sim sculptures my founder had made, but my dear founder just finished the very first ice sculptur of gen 6 and the value has the same as it was for gen 4 and 5, so apparently it does matter how many sims you sculptured. Founder has done 288 so far, I noticed that they had jumped in value at around 200 made.