I'm actually going to disagree with the initial price for this: nullbinos are fun for people who like to coordinate the colors of their cats with the wind or personality icons but since they can't breed they aren't useful for the albino breeding that many people are buying albinos for, so they aren't worth as much as you might expect. If this was a g1 cat it might be different, but since it's g2 it already has filled in family and can't follow the aesthetic for a completely empty sheet cat (no color, no family, no friends) and there's plenty of purposeful or accidental g2 nullbinos that pop up here and there. From what I've seen, the pricing for a g2 nullbino should be similar to a g2 longhair bino of the same white type since the genetic chances for null are the same as two longhair carrying parents. For g2+ classic albinos that would be about 25k.
Here's a recent reserve for a classic nullbino that is g2+ which quotes a discord price check.
edit: for most people, g2 is the same as g2+, but since your kitty still has a fairly small family you might be able to get a higher price if the buyer is sure the family list will stay small. If you're planning on growing the family though then this doesn't matter.