I actually don't know much about chicks but quail is close in nutritional value to rats (not as many vitamins but protein is better and less ash I believe) I also know that studies of ball pythons in the wild in the northern end of the range has turned up in sub-adult (under 28" I think if I remember correctly) a large proportion of avian species, doves, parrots, weavers and a handful of others. There is some evidence that avians are actually not that out of the normal diet. The report also states that over 28" the majority of prey is small rodents, shrews, ASFs, giant rat, grass mouse, and squirrels.

Luiselli, L, Akani, G C, & Capissi, D Journal of Zoology, London, 1998 Food Resource Partitioning of a community of snakes in a swamp rainforest of south-eastern Nigeria.

I think there is some support to quail (chicks are not great value) but still at some point they will need to be switched. Rats are great all rounders, easy and available I see no particular reason to start on something else especially if they have been started or rats or mice. The argument of money upsets me personally as I believe that there is great responsibility in caring for a living creature. The cost of care should have been one of the 100 other thoughts that were planned for before the commitment was made. I understand that times change but to start out trying to cut costs makes a poor start.