The reason why Momiji is cheap is because individuals that performed badly in badge screenings, or have bad lineage are collected for this purpose
Shopowners fully understand that these "disqulified" Momiji cannot be educated by children (the primary target demographic for the cheap Momiji), and sell them with this in mind.
In other words, this is done so that the Momiji that have been sold
and thrown away (by children who have lost patience in educating them) would get re-collected and sent to the factory.
Afterwards, the collected Momiji are injected with a growth-inducing drug, and got reused in mass-producing food-grade Momiji.