diff --git a/app/models/input.rb b/app/models/input.rb
index 541fbc4..df88ac6 100644
--- a/app/models/input.rb
+++ b/app/models/input.rb
@@ -9,6 +9,8 @@ class Input < ActiveRecord::Base
 
   belongs_to :unit
 
+  named_scope :relevant_to_price, :conditions => { :relevant_to_price => true }
+
   include FloatHelper
 
   def price_per_unit=(value)
diff --git a/app/models/product.rb b/app/models/product.rb
index 9d74d19..5040c7a 100644
--- a/app/models/product.rb
+++ b/app/models/product.rb
@@ -175,7 +175,7 @@ class Product < ActiveRecord::Base
 
   def inputs_cost
     return 0 if inputs.empty?
-    inputs.map(&:cost).inject { |sum,price| sum + price }
+    inputs.relevant_to_price.map(&:cost).inject { |sum,price| sum + price }
   end
 
   def total_production_cost
diff --git a/test/unit/input_test.rb b/test/unit/input_test.rb
index 470b2f5..c136dab 100644
--- a/test/unit/input_test.rb
+++ b/test/unit/input_test.rb
@@ -177,4 +177,18 @@ class InputTest < ActiveSupport::TestCase
     assert_equal 0.00, input.cost
   end
 
+  should 'list inputs relevants to price' do
+    product_category = fast_create(ProductCategory)
+    product = fast_create(Product, :product_category_id => product_category.id)
+
+    i1 = Input.create!(:product => product, :product_category => product_category, :relevant_to_price => true)
+
+    i2 = Input.create!(:product => product, :product_category => product_category, :relevant_to_price => false)
+
+    i1.save!
+    i2.save!
+    assert_includes Input.relevant_to_price, i1
+    assert_not_includes Input.relevant_to_price, i2
+  end
+
 end
--
libgit2 0.21.2