Hello Thomas.

Thank you for reaching out to us.

I'm sorry to disappoint you, but unfortunately, something like this is not yet possible. The fastest way would be to access the database table "wp_wpdatatables_columns" and filter this table per the table ID. Please note that "wp_" is the default database prefix, but on your end, it could be anything, so look for "your_prefix_wpdatatables_columns". 

For example, if I'm editing the wp_wpdatatable_1:

Scroll to the right, and you'll see this column:

That's the prefix so it'd be a lot faster to apply the prefix through the database than opening column settings for each column.

You can also run this query:

UPDATE wp_wpdatatables_columns
SET    text_before = '$';

After that, you'd only need to remove this value from the wdt_ID column as that's the ID column of manual tables, and any other columns where you don't want this prefix.

I hope that helps.