It'll be unfair to say the ID or contractor had marked up from his cost somewhere to give FOC items, they marked up every cost their subcontractors charge them, it's only how much they mark up and it;s fair they mark up reasonably. Free items will still eat into their profits, but it's also a gimmick to let the owners feel more shiok,, cos the word 'free' makes people happier.
I'm doing sales so i guess all sales gimmicks are the same.