You can search "hatching bags" , the plastic mesh bags like fruit comes in. They will hold about 10 to 12 eggs, provide adequate airflow, and contain the hatched chicks without causing harm to them. I have seen them from 50 cents each to a roll of 100 for $12 on ebay
What numbers are you figuring your hatch rate with? Total number of eggs hatched out of total eggs set or total hatched out of total number that developed?