diff --git a/poizonstore/utils.py b/poizonstore/utils.py
new file mode 100644
index 0000000..e411fb0
--- /dev/null
+++ b/poizonstore/utils.py
@@ -0,0 +1,6 @@
+from rest_framework.fields import DecimalField
+
+
+class PriceField(DecimalField):
+    def __init__(self, *args, max_digits=10, decimal_places=2, min_value=0, **kwargs):
+        super().__init__(*args, max_digits=max_digits, decimal_places=decimal_places, min_value=min_value, **kwargs)
diff --git a/store/serializers.py b/store/serializers.py
index 94b4557..52700b9 100644
--- a/store/serializers.py
+++ b/store/serializers.py
@@ -6,6 +6,7 @@ from account.serializers import UserSerializer
 from utils.exceptions import CRMException
 from store.models import Checklist, GlobalSettings, Category, PaymentMethod, Promocode, Image, Gift
 from store.utils import get_primary_key_related_model
+from poizonstore.utils import PriceField
 
 
 class ImageSerializer(serializers.ModelSerializer):
@@ -36,7 +37,7 @@ class CategoryChecklistSerializer(serializers.ModelSerializer):
 
 
 class CategorySerializer(serializers.ModelSerializer):
-    chinarush = serializers.DecimalField(source='delivery_price_CN_RU', max_digits=10, decimal_places=2)
+    chinarush = PriceField(source='delivery_price_CN_RU')
 
     class Meta:
         model = Category
@@ -56,6 +57,7 @@ class CategoryFullSerializer(CategorySerializer):
 
 class GiftSerializer(serializers.ModelSerializer):
     image = Base64ImageField(required=False, allow_null=True)
+    min_price = PriceField()
 
     class Meta:
         model = Gift
@@ -79,17 +81,17 @@ class ChecklistSerializer(serializers.ModelSerializer):
     use_bonuses = serializers.BooleanField(write_only=True, default=False)
     gift = get_primary_key_related_model(GiftSerializer, required=False, allow_null=True)
 
-    yuan_rate = serializers.DecimalField(read_only=True, max_digits=10, decimal_places=2)
-    price_yuan = serializers.DecimalField(required=False, max_digits=10, decimal_places=2)
+    yuan_rate = PriceField(read_only=True)
+    price_yuan = PriceField(required=False)
     price_rub = serializers.IntegerField(read_only=True)
 
-    delivery_price_CN = serializers.DecimalField(read_only=True, max_digits=10, decimal_places=2)
-    delivery_price_CN_RU = serializers.DecimalField(read_only=True, max_digits=10, decimal_places=2)
+    delivery_price_CN = PriceField(read_only=True)
+    delivery_price_CN_RU = PriceField(read_only=True)
 
-    full_price = serializers.IntegerField(read_only=True)
-    real_price = serializers.DecimalField(required=False, allow_null=True, max_digits=10, decimal_places=2)
+    full_price = PriceField(read_only=True)
+    real_price = PriceField(required=False, allow_null=True)
 
-    commission_rub = serializers.DecimalField(read_only=True, max_digits=10, decimal_places=2)
+    commission_rub = PriceField(read_only=True)
 
     customer = get_primary_key_related_model(UserSerializer, required=False, allow_null=True)
 
@@ -237,15 +239,16 @@ class ClientUpdateChecklistSerializer(ClientChecklistSerializerMixin, ChecklistS
 
 
 class GlobalSettingsSerializer(serializers.ModelSerializer):
-    currency = serializers.DecimalField(source='full_yuan_rate', read_only=True, max_digits=10, decimal_places=2)
-    yuan_rate_last_updated = serializers.DateTimeField(read_only=True)
-    chinadelivery = serializers.DecimalField(source='delivery_price_CN', max_digits=10, decimal_places=2)
-    commission = serializers.DecimalField(source='commission_rub', max_digits=10, decimal_places=2)
+    yuan_rate = PriceField(source='full_yuan_rate', read_only=True)
+    yuan_rate_commission = PriceField()
+    chinadelivery = PriceField(source='delivery_price_CN')
+    commission = PriceField(source='commission_rub')
     pickup = serializers.CharField(source='pickup_address')
 
     class Meta:
         model = GlobalSettings
-        fields = ('currency', 'yuan_rate_last_updated', 'yuan_rate_commission', 'commission',  'chinadelivery', 'pickup', 'time_to_buy')
+        fields = ('yuan_rate', 'yuan_rate_last_updated', 'yuan_rate_commission', 'commission',  'chinadelivery', 'pickup', 'time_to_buy')
+        read_only_fields = ('yuan_rate_last_updated',)
 
 
 class AnonymousGlobalSettingsSerializer(GlobalSettingsSerializer):