class LearnTemp(search.SearchableModel):
    pid = db.ReferenceProperty(Product, collection_name='picks')
title = db.StringProperty()
description = db.TextProperty()
order = db.IntegerProperty()
order = db.IntegerProperty()
cost = db.FloatProperty(default=0.0)
cost1 = db.FloatProperty(default=0.0)
Измените IntegerProperty на FloatProperty существующего хранилища данных AppEngine.