The Greater/Lesser Mythos thing might be necessary because of the diversity we have. Apparently we want simple mythos, mythos that are a challenge for Heroes, and mythos that are a challenge for certain Spirits.
I would say keep the price for creating them the same and just limit everyone to a few (Possible one) Greater mythos.
Are you saying that a lesser mythos could become a hero now?
I'm not sure about the numbers yet, I'd have to look into it deeper.
Romans 8:31 What, then, shall we say in response to this? If God is for us, who can be against us?
1 Corinthians 13:1-3 If I speak in the tongues of men or of angels, but do not have love, I am only a resounding gong or a clanging cymbal. If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but do not have love, I am nothing. If I give all I possess to the poor and give over my body to hardship that I may boast, but do not have love, I gain nothing.