Hello, the way I'd go about this is to add a calculated custom field in the same custom form where the client budget field lives, say it's called 'Client Budget Calculated Field.' Have this field reference the client budget field with a calculation if budget greater or equal to X, show as Y. If less than A, show as B.
Then your grouping in the report would be grouping by this new 'Client Budget Calculated Field' Is Not Blank to pull in where this field has a value.
If this helped you, please mark correct to help others : )