My university education is in Clothing and textiles, I worked for a manufacturer and had a retail store for a while so my understanding of pricing I would say is fairly good. Here is the reason why sleep sacks and sleepwear cost more than day wear and why that matters.
Flammability testing.
It the seventies, it was decided to reduce injuries for children from fire in children's sleepwear. Traditional gowns made of gauzy cotton or flannel/ flannette are highly flammable. Cotton & rayon loose flowing gowns burn very quickly. I watched a video of cotton gown consume a toddler size mannequin in under 1minute. It is quite terrifying. Manufactures of sleepwear across the globe must conform to rigid standards for flammability. Higher standards mean higher testing costs, which trickles down to the retail level as higher retail prices.
That why I keep way from producing and selling sleep sacks and sleepwear for children. People are not always aware and will sewn up beautiful little house on the prairie inspired gowns for little girls, I think, unaware that it is illegal to sell these without insuring the fabric meets the flammability standard. So beware when shopping the handmade market for these types of products.
