well it is all in the color. bright colors and good banding makes a good woma. darker colors and banding that is mushed together is not so good. its like any type of snake....the more that area available the less expensive they will be. black heads are a great example of this. they are up there right now but im sure the price will drop.
here is a site of a breeder who breeds womas and others. look at the coloring and banding on these. his average prices are like i said 400-800 dollars depending on the qualit of the animal. http://www.millerreptiles.com/Womas/Womas.html
i don't have a womas yet but i will be getting some as soon as i can. will i pay the extra hundy for a brighter, better patterned animal......you bet i will!!