Thanks, Dave!
Bill likes to answer such questions with "There is no true color - only what your eye sees on a particular day with particular lighting on a particular subject." Pretty much what Dave said.
That photo was taken a few years ago at Chuck and Connie's (Pritzel) house, of their best hypo lav. It was one of their most photogenic snakes and was as nice of a lavender as I have seen. Certainly all lavs don't look like that. However, males, especially hypos, usually show more of the pinks that enhance the lav look, as compared to females and regular (not hypo) lavs. It was taken in an outdoor setup behind their house, in the shade, with fill flash. Bill did not enhance the color in Photoshop, but the color was fully saturated because of shooting in shade or on an overcast day, using fill flash.
So in full sunshine, the snake's colors might have looked more washed out as in one of the photos in this thread. But in the conditions we shot in (shade, with flash), it looked much as in the photo. Of course, if you put that same snake in a typical living room, the incandescent lights will give it a yellowish tinge. But put those purple plant lights over the cage, and any snake with pink, red or orange will just GLOW! So don't always expect the same snake to look the same way in different conditions, especially with some of the more delicate pink colors. I have seen this to be even more true when photographing pink snow corns. It is really difficult to capture the pink without either washing it out, or turning it neon, depending on the lighting.
In summary, if you want a nice lavender, buy a male hypo lav and ask to see the parents, especially the dad. The pink color develops more as they age, so dad might be a good indicator of what to expect.
Hope that helps!