I've heard of people feeding chicks every once in a while to add a little variety, but I've never found a valid claim that it does anything to benefit the snake. I would think that it would be bad for the snake, because everyone I've ever encountered that fed birds to their snake says that it makes their poop runny and really stinky.

I would think buying rats or mice in bulk would be cheaper than chicks anyway. On RodentPro's site, for example, a bag of 100 pinkie rats that weigh 3-9 grams costs $0.50 per rat, whereas a bag of 10 small chicks weighing 2-6 grams costs $1.00 per chick. Mice are even cheaper; they don't even hit .50 each until they've over 13 grams.