A little fiddle to parse a decimal string in the context of multiple cultures.

makeDoubleGreatAgain.vb

Imports System
				
Public Module Module1
	Public Sub Main()
		Console.WriteLine(Decimal.Parse("-2"))
		Console.WriteLine(MakeDoubleGreatAgain("-3.33"))
	End Sub
	
	    'Parse assorted cutlures for doubles
    Public Function MakeDoubleGreatAgain(value As String) As Double
	    Dim style As System.Globalization.NumberStyles
	    Dim number As Decimal = 0

		style = System.Globalization.NumberStyles.AllowDecimalPoint Or System.Globalization.NumberStyles.AllowThousands Or System.Globalization.NumberStyles.AllowLeadingSign
	    Dim cultures() As String = {"fr-FR", "en-US", "en-GB", "es-ES"}
	    For Each culture As String In cultures
		    If [Decimal].TryParse(value, style, System.Globalization.CultureInfo.CreateSpecificCulture(culture), number) Then
			    Exit For
		    End If
	    Next

	    Return number
    End Function
End Module

parseInternationalNumbers.cs

using System;
using System.Globalization;

public class Program
{
	public static void Main()
	{
		Console.WriteLine(MakeStringGreatAgain("2.234.234,12"));
	}
	
	public static string MakeStringGreatAgain(string value){
		NumberStyles style;
		decimal number = 0;

		style = NumberStyles.AllowDecimalPoint | NumberStyles.AllowThousands | NumberStyles.AllowLeadingSign;
		var cultures = new[] {"fr-FR", "en-US", "en-GB", "es-ES"};
		foreach (var culture in cultures)
		{
			if (Decimal.TryParse(value, style, CultureInfo.CreateSpecificCulture(culture), out number))
				break;
		}

		return number.ToString();
	}
}

Added VB version and added NumberStyles.AllowLeadingSign so negatives convert correctly instead of going to zero