When doing Batch updates for pricing, I often want to update a large category of products and exempt a small subcategory from that selection. The current workaround is to change all the prices of the large selection, then change back the subcategories which does eventually work once the queue processes. However by allowing us to choose "Not" for a box, it will reduce the server processing load by reducing the volume of products that we want to change, and removing the possibility of one of the "Not" categories being priced incorrectly while the second process completes.
I would like to see it implemented as a slash through the selection box available by toggling it twice, so the first click would "check" the box, the second click would "-" the box, or perhaps "x", and the third click would return it to un-selected. Presumably this feature could also be applied to the front end of the websites so card-searching could be more efficient, as it is on Magic: Gatherer. It would allow customers to search for cards limited to color identities such as "Planeswalkers that do not have Red in them" where as currently if you select all of the other colors other than red, you'll get cards that have those colors plus red.
