I don't think you can put a "reasonable" price on this because "worth" is in the eye of the beholder. It's only worth what you are willing to pay for it (or part with it as the case may be.)
Since each pin was $4 the retail cost was $416 (plus any tax someone paid). These pins went on sale, so it's possible that the set didn't even cost that much to purchase.
Again, it is only worth what someone is willing to pay for it.
Sue Ellen