Around 20 dollars or so, maybe less. Look at their eyes and nostrils to be sure they're clear, flip them over and look at their butts, vents should be clear without large amounts of poo sticking to them. When you pick the chickens up they should feel heavy, not light and bony. Open their wings and look under their "armpits" where the feathers are thin, skin should be clean with no parasites. Leg scales should be closed and smooth. Combs should be bright red. Overall appearance of alertness and health. Puffed up in a corner is not healthy. Ask how old it is, chickens over 3 years old usually start slowing down laying eggs. An older chicken will have a whiter beak and legs as the yellow fades.