это должно сделать это.
add_filter( 'woocommerce_product_get_price', 'conditional_product_price', 10, 2 );
function conditional_product_price( $price, $product ) {
if ( is_admin() ) { return $price; }
$units_sold = $product->get_total_sales();
$price_addition = 1; // for 1€
remove_filter( 'woocommerce_product_get_price', 'conditional_product_price', 10, 2 );
$price = ( $product->is_on_sale() ? $product->get_sale_price() : $product->get_price() ) + ( $units_sold * $price_addition );
add_filter( 'woocommerce_product_get_price', 'conditional_product_price', 10, 2 );
return $price;
}