The price of poultry cages are insane...down at the local feed store. 50 some odd dollars for a cage.....so that you can transport a $12.00 chicken? Don't get me wrong...I am not a cheap skate....but I am not Howard Hughes either.
My solution.....take a plastic milk case.....cut a piece of plywood out for a cover door. Leave gaps as seen on both sides...the chickens like to poke their heads out.......making sure that they not heading to a butcher shop.
Drill a few holes as seen in the picture.....two in the rear...one up front. Secure the two rears with plastic ties (acts like a henge).....the front hole you'll use a tie once the chicken is placed into the cage.
Transport.