Ok- as long as their the same age I am sure that they will get along just fine. :hugs
My Cockerel Quill is going to be larger than two of the three pullets- so I get your concern.
It depends on the breed. If they are a larger or rare breed - they will be a higher cost. Cheaper breeds, such as Brown and White Leghorns- are lower cost because of how common they are. It will also depend on if they are sexed or straight runs.