Time was one could have vintage detergents for less than one dollar, but times have changed and some dealers seem to believe they are selling gold nuggets. Then there was the member who spied several boxes of vintage detergent at an estate sale, only to have his head handed to him, promply told off and asked to leave by the seller. Apparently those boxes of detergent were "spoken for" and our poor member trod on someone's toes by having the nerve to try and buy something at a sale.
If you really wish the detergent, then no price is to great, so it is really your call. Someone was selling vintage boxes of Oxydol detergent several months ago on fleaBay, and couldn't believe the prices paid.
L.