If you have a poultry supplier nearby you may be able to get chicken carcasses, necks, wings etc in bulk, I buy carcasses in 5kg bags for the ferrets and dogs, I pay £1.50 per bag. You could also get some frozen rats or mice from most pet shops, they're great ferret food as they are whole prey items and a more balanced, complete meal.
I feed my ferrets and dogs a mixture of raw chicken, mice, rats, fish, eggs, lamb, beef, pork (which is safe to feed these days as methods of rearing, slaughter and butchery are different and a ferrets stomach is very acided so parasites have a hard time to surv