Every pos het should be mentioned to the purchaser in my opinion. It will only muddy up genetics when that new purchase sells their babies and continues to pass on genetics and not be aware of it. However, I think that the originally seller should not be adjusting prices for pos hets. Unless it is 100%, a het should never have a raised price in my opinion. Them purchasing that gecko is a gamble to catch that gene as is...why inflate the price for that gamble?
i got two normal geckos from a pet store and breed them and hatch out two blazing blizzards. i think pet stores should tell you who hatched the geckos.