For a large range of prices and availability look at kingsnake.com or faunaclassifieds.com. They host a massive amount of low to high end animals from a variety of different breeders. Just remember just because someone is selling a female pastel for $90 it doesn't mean it has the same qualities as other female pastels.
Each individual example of a morph has qualities buyers are looking for that justify the price, sometimes you are able to find great deals of exceptional examples of morphs if you spend a decent amount of time looking around or a visit local reptile shows to save on shipping costs.
Have fun hunting for your next purchase!