Okla. Stat. tit. 68, § 68-339: Cost survey; admissibility

a. Where a cost survey, pursuant to recognized statistical and

cost accounting practices, has been made for the trading area in

which the offense is committed, to establish the lowest "cost to the

retailer" and the lowest "cost to the wholesaler", said cost survey

shall be deemed competent evidence to be used in proving the cost to

the person complained against, within the provisions of this act.

b. Any defendant, or any witness, in any civil action brought

under the provisions of this act, may be required to testify, and

the books, records, invoices, and all other documents of any such

defendant, may be brought into court and introduced as evidence, but

no defendant, or any witness in any such civil action, shall be

prosecuted or subjected to any penalty or forfeiture for or on

account of any transaction, matter or thing concerning which he may

testify or produce evidence, documentary or otherwise, and no

testimony given or produced shall be received against him upon any

criminal proceeding or investigation.