Because it takes a long process of breeding, cross-breeding, buying new snakes so the gene line doesn't become inbred, and hundreds of hours of work to produce a single morph snake. You can't just toss a bunch of snakes in together and come back 10 weeks later to a bunch of babies with all sorts of morphs. Most morphs are exorbitantly priced for these same reasons.
I'd be wary of any snake selling for much less than the standard price, even if it were from someone as well-known as Alex Hue.