full implementation of B2B_OFFER_CHANGE, some small code cleanum may still be needed.

Code tested with realtime data from amazon

Author: CrineTech

Source/FikaAmazonAPI/NotificationMessages/BuyBoxPriceB2B.cs

@@ -0,0 +1,6 @@
+namespace FikaAmazonAPI.NotificationMessages
+{
+    public class BuyBoxPriceB2B : PriceBaseB2B
+    {
+    }
+}

Source/FikaAmazonAPI/NotificationMessages/BuyBoxPriceB2C.cs

@@ -0,0 +1,6 @@
+namespace FikaAmazonAPI.NotificationMessages
+{
+    public class BuyBoxPriceB2C : PriceBaseB2C
+    {
+    }
+}

Source/FikaAmazonAPI/NotificationMessages/LowestPriceB2B.cs

@@ -0,0 +1,16 @@
+using Newtonsoft.Json;
+
+namespace FikaAmazonAPI.NotificationMessages
+{
+    public class LowestPriceB2B : PriceBaseB2B
+    {
+        /// <summary>
+        /// Required. Indicates whether the item is fulfilled by Amazon or by the seller.
+        /// </summary>
+        /// <remarks>
+        /// See values from FulfillmentChannelType class.
+        /// </remarks>
+        [JsonProperty("FulfillmentChannel")]
+        public string FulfillmentChannel { get; set; }
+    }
+}

Source/FikaAmazonAPI/NotificationMessages/LowestPrice.cs renamed to Source/FikaAmazonAPI/NotificationMessages/LowestPriceB2C.cs

@@ -6,7 +6,7 @@ namespace FikaAmazonAPI.NotificationMessages
     /// <summary>
     /// An explanation about the purpose of this instance.
     /// </summary>
-    public partial class LowestPrice : BuyBoxPrice
+    public partial class LowestPriceB2C : PriceBaseB2C
     {
         /// <summary>
         /// Required. Indicates whether the item is fulfilled by Amazon or by the seller.

Source/FikaAmazonAPI/NotificationMessages/Price.cs

@@ -2,11 +2,7 @@
 
 namespace FikaAmazonAPI.NotificationMessages
 {
-
-    /// <summary>
-    /// An explanation about the purpose of this instance.
-    /// </summary>
-    public partial class BuyBoxPrice
+    public abstract class PriceBase
     {
         /// <summary>
         /// Required. ListingPrice + Shipping - Points. 
@@ -26,15 +22,6 @@ public partial class BuyBoxPrice
         [JsonProperty("Shipping")]
         public MoneyType Shipping { get; set; }
 
-        /// <summary>
-        /// Optional. The number of Amazon Points offered with the purchase of an item. 
-        /// </summary>
-        /// <remarks>
-        /// Note: The Points object is only returned in Japan (JP).
-        /// </remarks>
-        [JsonProperty("Points", NullValueHandling = NullValueHandling.Ignore)]
-        public Points Points { get; set; }
-
         /// <summary>
         /// Required. Indicates the condition of the item. For example: New, Used, Collectible, Refurbished, or Club. 
         /// </summary>

Source/FikaAmazonAPI/NotificationMessages/BuyBoxPrice.cs renamed to Source/FikaAmazonAPI/NotificationMessages/PriceBase.cs

@@ -0,0 +1,31 @@
+using Newtonsoft.Json;
+
+namespace FikaAmazonAPI.NotificationMessages
+{
+    public abstract class PriceBaseB2B : PriceBase
+    {
+        /// <summary>
+        /// Required. Indicates whether the offer is a B2B offer or a B2C offer. When the offer type is B2C in a quantity discount, the seller is winning the Buy Box because others do not have inventory at that quantity, not because they have a quantity discount on the ASIN.
+        /// </summary>
+        [JsonProperty("OfferType")]
+        public string OfferType { get; set; }
+
+        /// <summary>
+        /// Required. The quantity tier for the offer.
+        /// </summary>
+        [JsonProperty("QuantityTier")]
+        public int QuantityTier { get; set; }
+
+        /// <summary>
+        /// Optional. Indicates whether the quantity tier is for Quantity Discount or Progressive Discount.
+        /// </summary>
+        [JsonProperty("DiscountType")]
+        public string DiscountType { get; set; }
+
+        /// <summary>
+        /// Optional. The seller identifier for the offer.
+        /// </summary>
+        [JsonProperty("SellerId")]
+        public string SellerId { get; set; }
+    }
+}

Source/FikaAmazonAPI/NotificationMessages/PriceBaseB2B.cs

@@ -0,0 +1,20 @@
+using Newtonsoft.Json;
+
+namespace FikaAmazonAPI.NotificationMessages
+{
+
+    /// <summary>
+    /// An explanation about the purpose of this instance.
+    /// </summary>
+    public abstract class PriceBaseB2C : PriceBase
+    {
+        /// <summary>
+        /// Optional. The number of Amazon Points offered with the purchase of an item. 
+        /// </summary>
+        /// <remarks>
+        /// Note: The Points object is only returned in Japan (JP).
+        /// </remarks>
+        [JsonProperty("Points", NullValueHandling = NullValueHandling.Ignore)]
+        public Points Points { get; set; }
+    }
+}

Source/FikaAmazonAPI/NotificationMessages/PriceBaseB2C.cs

@@ -5,6 +5,24 @@ namespace FikaAmazonAPI.NotificationMessages
 {
     public class SummaryB2B : SummaryBase
     {
+        /// <summary>
+        /// Required. A list that contains the lowest prices of the item for the given conditions, fulfillment channels, quantity tiers, and discount types.
+        /// </summary>
+        /// <remarks>
+        /// The seven pre-defined quantity tiers for discount type “Quantity Discounts” are 2, 3, 5, 10, 20, 30 and 50.
+        /// </remarks>
+        [JsonProperty("LowestPrices")]
+        public List<LowestPriceB2B> LowestPrices { get; set; }
+
+        /// <summary>
+        /// Optional. A list that contains the Buy Box price of the item for the given conditions, quantity tiers, and discount types.
+        /// </summary>
+        /// <remarks>
+        /// Up to the first 50 quantity tiers are shown.
+        /// </remarks>
+        [JsonProperty("BuyBoxPrices")]
+        public List<BuyBoxPriceB2B> BuyBoxPrices { get; set; }
+
         /// <summary>
         /// Required. A list that contains the total number of offers that are eligible for the Buy Box for the given conditions and fulfillment channels.
         /// </summary>

Source/FikaAmazonAPI/NotificationMessages/SummaryB2B.cs

@@ -5,6 +5,18 @@ namespace FikaAmazonAPI.NotificationMessages
 {
     public class SummaryB2C : SummaryBase
     {
+        /// <summary>
+        /// Required. A list that contains the lowest prices of the item for the given conditions and fulfillment channels.
+        /// </summary>
+        [JsonProperty("LowestPrices")]
+        public List<LowestPriceB2C> LowestPrices { get; set; }
+
+        /// <summary>
+        /// Optional. A list that contains the Buy Box price of the item for the given conditions.
+        /// </summary>
+        [JsonProperty("BuyBoxPrices")]
+        public List<BuyBoxPriceB2C> BuyBoxPrices { get; set; }
+
         /// <summary>
         /// Optional. The list price of the item as suggested by the manufacturer.
         /// </summary>