In general most people are not willing to pay the asking price for a pullet or hen that has been raised and is producing a sky blue egg shell. Even then, sky blue is in the eyes of the beholder . . . there are a lot of different shades of blue in the sky! LOL
In general, most folks forget about the male bird\'s genetics in the egg shell color department. Not just any old cock or cockerel will due, the best will be a cock that is proven. He has been crossed on a leghorn to check for brown genes and has proven that he can produce daughters with sky blue egg shell color. Again, price is the issue here . . . you are buying a cock that has a lot of time and effort in him.
So, you have several options . . .
1. Buy lots of hatching eggs so you have visual proof of the quality of the egg color the chicks hatch out of, but you will be going on faith that the cock/cockerel had the appropriate genes.
2. Buy lots of chicks and cull pullets heavily and genetic test all cockerels before use.
3. Make friends with a breeder in your area and get on the waiting list for birds that the breeder will have with good egg color that he or she is willing to sell over the years.
The egg shell color of Ameraucana varieties depends on the line and very wildly. I would make friends with those in your area with blue wheaten and buy some eggs and compare the shell color and then pick the line you like the best.
Best wishes!
Michael