There wouldn't be any easy ways to add the '*' before the amount word dynamically, since it's not really possible to get the position it's at.

If "amount" is going to be static, it may be best to just put the '*' into a second data selection, and manually place it next to "amount". Another possibility would be to use a superscripted font, if you have one. If you had one, you could use a combination of show and setstyle to do the superscripting.

Otherwise, there's no real way to do it. "True" superscripting is not supported in our software, so while in some cases it's possible to simulate it in PressTalk or by placing data selections/text objects containing the characters, in a paragraph-based text it's not really possible, unless you have a superscripted font.