The economist inside of me is cringing as I read the above posts.....
The morphs that carry the greatest demand are those that have the highest price. Examples being the plattys, super-whatevers, spiders, etc. The price is so high because the demand for those morphs far exceed the supply. I'm not saying thats the ONLY factor that determines the price of those guys, but its got a lot to do with it.
Pastels and albinos are somewhat less expensive because they are bred by more people and thus more readily available.
I'd probably guess that the morph with the highest demand is probaby NORMAL. Look at how many people have morphs vs. how many people have normals. The price on normals is so low because thye are being produced in numbers that meet that demand.
Kind of a trick question, huh?