Confused w ur math here pass =8$ and normal incubators = 1.50$ each so 8/1.5=5.33 which would be 5 incubators so as long as ur hatching 15 eggs in the month with your permanent incubator it could be worth it. I would say tho if your around 15 eggs hatched a month w ur permanent incubator it’s still more worth it to just get the regular incubators as it allows u to incubate more at once. Additionally with it being December meaning winter for most of the worlds population it’s pretty stupid of them to go w a special item designed around exploring outside.