//Ipmpelemtation of the custom format. 
//If the formatting value >= 1000, the resulting string will contain value, divised by 1000 with 'K' suffix
//If the formatting value >= 1000000, the resulting string will contain value, divised by 1000000 with 'M' suffix
public class SizeCustomFormat : IFormat
{
    public string Format(IDataField dataField)
    {
        decimal value = Convert.ToDecimal(dataField.Value);
        if (value >= 1000000)
        {
            value = value / 1000000;
            return value != 0 ? string.Format("{0:n2} M", value) : string.Empty;
        }
        if (value >= 1000)
        {
            value = value / 1000;
            return value != 0 ? string.Format("{0:n2} K", value) : string.Empty;
        }
        return value != 0 ? string.Format("{0:n2}", value) : string.Empty;
    }

    public bool CanParse(string text, IDataField dataField)
    {
        //verify, if the text can be parsed
        text = text.Replace("M", "");
        text = text.Replace("K", "");
        text = text.Trim();
        decimal value;
        if (!string.IsNullOrEmpty(text) && 
            decimal.TryParse(text, NumberStyles.Number | NumberStyles.Float | NumberStyles.AllowLeadingSign, CultureInfo.InvariantCulture, out value))
        {
            return true;
        }
        return false;
    }

    public void Parse(string text, IDataField dataField)
    {
        //parse the text
        if(!string.IsNullOrEmpty(text))
        {
            decimal multiplier = 1;
            if(text.Contains("M"))
            {
                text = text.Replace("M", "");
                multiplier = 1000000;
            }
            else if (text.Contains("K"))
            {
                text = text.Replace("K", "");
                multiplier = 1000;
            }
            text = text.Trim();
            decimal value;
            if(decimal.TryParse(text, NumberStyles.Number|NumberStyles.Float|NumberStyles.AllowLeadingSign, CultureInfo.InvariantCulture, out value))
            {
                value *= multiplier;
                if (multiplier > 1)
                {
                    value = Decimal.Truncate(value);
                }

                //Set value to the field with the appropriate type
                dataField.Value = Convert.ChangeType(value, dataField.FieldType);
            }
        }
    }

    public object Clone()
    {
        return new SizeCustomFormat();
    }
}


//Some data object
public class Product
{
    private decimal price;

    [Format(typeof(SizeCustomFormat))]
    public decimal Price
    {
        get { return price; }
        set { price = value; }
    }
}


public void PopulateGrid(Grid grid)
{
    //Initialize the grid
    grid.Headers.Add(new Header());
    grid.Headers[0].Add(new Column("Price"));

    //By default, all grids use the formats are set trough the FormatAttribute.
    //Another way to set the format only for the specified column is to use the property Column.Format.
    //grid.Headers[0]["Price"].Format = new SizeCustomFormat();

    Product product = new Product();
    grid.Rows.Add(product);


    //Formatting data
    product.Price = 12469723.46654m;
    Console.WriteLine("The cell displays the text: {0}", grid.Rows[0]["Price"].Text);

    product.Price = 469723.46654m;
    Console.WriteLine("The cell displays the text: {0}", grid.Rows[0]["Price"].Text);

    product.Price = 723.46654m;
    Console.WriteLine("The cell displays the text: {0}", grid.Rows[0]["Price"].Text);

    //Parsing text
    grid.Rows[0]["Price"].Text = "123.654";
    Console.WriteLine("The product price: {0}", product.Price);

    grid.Rows[0]["Price"].Text = "123.654 K";
    Console.WriteLine("The product price: {0}", product.Price);

    grid.Rows[0]["Price"].Text = "123.654 M";
    Console.WriteLine("The product price: {0}", product.Price);
}

//Output:
//The cell displays the text: 12,47 M
//The cell displays the text: 469,72 K
//The cell displays the text: 723,47
//The product price: 123,654
//The product price: 123654
//The product price: 123654000