Where a cost survey pursuant to recognized statistical and cost accounting practices has been made for the trading area in which a violation of this article is committed or charged to determine and establish on the basis of actual existing conditions the lowest cost to stampers or wholesalers or lowest cost to retailers within the area, such cost survey shall be deemed competent evidence in any action or proceeding under this article as tending to prove actual cost to the stamper or wholesaler or to the retailer complained against. Any party against whom any such cost survey may be introduced in evidence shall have the right to offer evidence tending to prove any inaccuracy in such cost survey or any state of facts which would impair its probative value.