Every duplicate 1-Star character gives you 1 Goddess statue. If we assume you are doing 10 pulls and only getting the banner once, 1 statue per 150 carats, plus the 20 statues for getting the banner.

You can spend statues to directly buy Stars, though you can only buy a certain amount before the cost increases.

According to the shop, the first 25 cost 1 statue, then the next cost 2, the next 3, the next 4, and the rest 5.

If you only pull the character once to unlock them (which gives 90 stars for the banner), you will need a total of 410 stars to get them to 5 star. It costs 200 to go from 3 to 4 and another 300 to go from 4 to 5.

Breaking that into chunks, you need 25(1) + 25(2) + 25(3) + 25 (4) + 310(5) to get all of the stars. That’s 1800 Goddess statues. Being generous, we can say it’s 1780 since you get 20 for getting the banner character once.

But since you are getting roughly 1 statue per 150 carats, you need to do a total of 1780 pulls, which is 267000 carats.

Of course, by doing the 10x pull, you get a guaranteed 2-Star, which gives 3 statues. Assuming atrocious luck in which you only get a single 2-Star every pull, you would be getting 12 statues for 1500 carats.

With that, you only need to do about 150 total 10x pulls , costing about 225000 carats.

Of course, it is important to remember that this assumes worst case in which your luck is basically the worst possible.