Change woocommerce sales price programmatically

wc_change_sales_price.php

<?php
// Your Product ID
$product_id		= 57;

$ecd_product	=	new WC_Product( $product_id );

/**
 * Check if product exists
 */
if( $ecd_product->exists() ){

  /**
   * Get current (discounted) sales price for calculations etc
   */
  $ecd_product->sale_price;

  /**
   * Get regular price for calculations etc
   */
  $ecd_product->regular_price;

  /**
   * Get price (the actually price that people will pay)
   * NOTE: If you set sales price different, this should be same as sales price
   */
  $ecd_product->price;

  /**
   * Update sales price to $10
   */
  $sp	=	update_post_meta( $ecd_product->id, '_sale_price', '10' );
  $p	=	update_post_meta( $ecd_product->id, '_price', '10' );

  if( $sp && $p ){
    echo 'Sales price is $10 now!';
  }

}