SMA Technical Indicator

I saw a question on MSDN Forums about having real-time SMA indicator. So even if I never used this indicator in real systems, I know it's simplest one and decide to develop it. So here it is:

public class SMA
{
    private readonly int _Length;
    private readonly bool _StoreData;
    private decimal _Value;
    private decimal _Price;
    private bool _Primed;
    private readonly string _Name;
    private readonly DecimalCollection _PriceArray = new DecimalCollection();
    private readonly DecimalCollection _ValueArray = new DecimalCollection();

    public SMA(int length) : this(length, false)
    {
    }

    /// <summary>
    /// Class for calculating Simple Moving Average
    /// </summary>
    /// <param name="length">Lenght SMA calculation formula</param>
    /// <param name="storeData"></param>
    public SMA(int length, bool storeData)
    {
        _Length = length;
        _StoreData = storeData;
        _Name = GetType().Name + Length;
    }

    public int Length
    {
        get { return _Length; }
    }

    public bool StoreData
    {
        get { return _StoreData; }
    }

    public decimal Value
    {
        get { return _Value; }
    }

    public bool Primed
    {
        get { return _Primed; }
    }

    public string Name
    {
        get { return _Name; }
    }

    public DecimalCollection ValueArray
    {
        get { return _ValueArray; }
    }

    public void PriceTick(decimal price, bool add)
    {
        if (add)
            AddPrice(price);
        else
            EditPrice(price);
    }

    public void PriceTicks(DecimalCollection prices)
    {
        if (prices == null || prices.Count == 0)
            return;
        for (int i = 0; i < prices.Count; i++)
        {
            AddPrice(prices[i]);
        }
    }

    private void AddPrice(decimal price)
    {
        _Price = price;
        if (!_Primed)
        {
            _PriceArray.Add(_Price);
            if (_PriceArray.Count == Length)
            {
                _Primed = true;
                _Value = _PriceArray.Average();
            }
        }
        else
        {
            _PriceArray.RemoveAt(0);
            _PriceArray.Add(price);

            _Value = _PriceArray.Average();

            if (_StoreData)
            {
                ValueArray.Add(_Value);
            }
        }

    }

    private void EditPrice(decimal price)
    {
        if (price != _Price)
        {
            _Price = price;

            _PriceArray[_PriceArray.Count - 1] = _Price;

            if (_Primed)
            {
                if (_PriceArray.Count == _Length)
                {
                    _Value = _PriceArray.Average();
                    if (_StoreData)
                    {
                        ValueArray[ValueArray.Count - 1] = _Value;
                    }
                }
                else
                {
                    _Value = _PriceArray.Average();
                    if (_StoreData)
                    {
                        ValueArray[ValueArray.Count - 1] = _Value;
                    }
                }
            }
        }
    }
}

This source uses DecimalCollection class that is already published on my blog.