What is "The Best" U.S. Currency RegEx?

Question

A quick search for currency regex brings up a lot of results.

The problem I have in choosing one is that regex is difficult to verify without testing all the edge cases. Does anyone have a regex for U.S. currency that has been thoroughly tested?

My only requirement is that the matched string is U.S. currency and parses to System.Decimal:

[ws][sign][digits,]digits[.fractional-digits][ws] 

Elements in square brackets ([ and ]) are optional. 
The following table describes each element. 

ELEMENT             DESCRIPTION
ws                  Optional white space.
sign                An optional sign.
digits              A sequence of digits ranging from 0 to 9.
,                   A culture-specific thousands separator symbol.
.                   A culture-specific decimal point symbol.
fractional-digits   A sequence of digits ranging from 0 to 9. 

Answer 1

here's some stuff from the makers of Regex Buddy. These came from the library so i'm confident they have been thoroughly tested.

Number: Currency amount (cents mandatory) Optional thousands separators; mandatory two-digit fraction

Match; JGsoft:
^[+-]?[0-9]{1,3}(?:,?[0-9]{3})*.[0-9]{2}$

Number: Currency amount (cents optional) Optional thousands separators; optional two-digit fraction

Match; JGsoft:
^[+-]?[0-9]{1,3}(?:,?[0-9]{3})*(?:.[0-9]{2})?$

Number: Currency amount US & EU (cents optional) Can use US-style 123,456.78 notation and European-style 123.456,78 notation. Optional thousands separators; optional two-digit fraction

Match; JGsoft:
^[+-]?[0-9]{1,3}(?:[0-9]*(?:[.,][0-9]{2})?|(?:,[0-9]{3})*(?:.[0-9]{2})?|(?:.[0-9]{3})*(?:,[0-9]{2})?)$