Does it work if you use the PDF Comments panel instead?

Using InDesign’s PDF Comments Panel

Well, you wanted to include the $ symbol, so no, not really. Positive Lookbehind would be for something like: “Find a digit that comes immediately after a $ — but don’t include the $ symbol.”

Though you could use a negative lookahead, for example, to say “find any number unless it is followed by a # symbol.”

Yeah, this can be tricky, depending on what you want/need.
CC Libraries has a way to link to text that needs to be updated. But it’s hard to link to formatted text. Does it need to be formatted?

Here’s an old post on the subject (that doesn’t include cc libraries because it was written before that feature):

Updating Bits of Text Across Multiple Documents