There are use cases when the revenue needs to be populated as the Classification value. It requires the usage of currency symbols, for example, $ for USD.
Usage of USD $2500 - $3000 for regex as the Classification value in a rule in the Classification Rule Builder will return an error. This is because the $ symbol denotes the end of the key in Regular Expressions.
Space can be used to escape $. For instance, a space between $ and the number will resolve the issue.
Example: USD $ 2500 - $ 3000