Update: There is a newer version of the GroBaby and a newer video of gDiapers
Here is how I came up with the figures you saw in the film:
I used this website to get the number of diaper changes a baby will need from birth to 30 months. Since G Diapers have 2 different sizes of flushable inserts I had to estimate the age they would switch from a small to a med/large. I used 4 months. So up to 4 months I used the amount of small flushable inserts that come in a package (40) and after 4 months I used 32, the number in a med/ large package. I then had to do the math. Say there are 990 changes in a 3 month period. I divided 990 changes by the number of flushable inserts in a pack (40) and multiplied that number by the cost of a package (14.49) This would be the cost of that time, and repeat for the many different stages. Then I had to add the cost of covers- the cheapest you can get a G diaper cover new is 16.99 so I used this number- to the total cost of the flushable inserts. I said 15 covers would be a good number, 5 for each size. My total number was 3,793.13 for G diapers using only flushable inserts- birth to 30 months.
For G diapers with prefolds I only had to calculate the total cost of 15 covers at 16.99 each, plus the cost of infant sized prefolds- about 24 prefolds. This came to only 296.85.
The Gro Baby was the easiest. I began adding the items individually which was well over 650 dollars. But most sites sell a package deal which includes 12 shells, 24 soakers, and 16 boosters. This is only 365.00. Since these are one size this is a onetime cost that lasts until potty training.
I did this comparison to help anyone out who is trying to choose between the two diapers. They are both great as a diaper bag diaper since they are less bulky. I hope this video was helpful!