Just for the sake of sharing prices in the context of North America— in Mexico 12 eggs go for $2.21 [1], 18 for $2.46 [2] and 30 for $4.90 [3]. This is just a normal supermarket, and the brand is just a common local one, not the cheapest and not the most expensive.

[1] https://www.soriana.com/huevo-blanco-bachoco-12-piezas/65002...

[2] https://www.soriana.com/huevo-blanco-bachoco-18-piezas/39041...

[3] https://www.soriana.com/huevo-blanco-bachoco-30-piezas/65002...