I would think even a male super pastel at 900 grams would be a bit over $200. A 900 gram female super pastel would easily be $300+. Check kingsnake, fauna classifieds, and the reptile report marketplace to give you a better idea.
1.0 2013 Firefly
1.0 2013 Black Pastel
1.0 2013 Cinnamon
0.1 2015 Leopard Butter Pastel
0.1 2015 Stinger Bee
0.1 2016 Pastel Pinstripe Disco Fire
0.1 2015 Dumeril's Boa