Convert.ToInt32() a string with Commas

You could use int.Parse and add the NumberStyles.AllowThousands flag:

int num = int.Parse(toParse, NumberStyles.AllowThousands);

Or int.TryParse letting you know if the operation succeeded:

int num;
if (int.TryParse(toParse, NumberStyles.AllowThousands,
                 CultureInfo.InvariantCulture, out num))
{
    // parse successful, use 'num'
}