Removing illegal characters for a Numeric Custom Field

If you have a value in an email such as $1,300.50 you may like to extract the numeric component and store in a suitable Numeric Custom Field.

Using the RegexpFP, just selecting the content of 1,300.50 will cause a failure when loading into the NumericCF type, it wont accept ','.  To work around this the following selector can be used:

This then only matches numeric and decimal point characters, commas and any alphabetical and symbolic characters would not match.  Its possible even with this that multiple . characters would be present, this will still break.