Integrating with the Easy Digital Downloads variable price advanced options in version 2.8

edd-variable-price-advanced-options-example.php

<?php

/**
 * Custom section for EDD price options
 */
function eddwp_custom_price_option_section( $post_id, $key, $args ) {
	$recurring = EDD_Recurring()->is_price_recurring( $post_id, $key );
	?>
	<div class="edd-custom-price-option-section">
		<span class="edd-custom-price-option-section-title">My Sample Extension</span>
		<div class="edd-custom-price-option-section-content">
			<span>
				<label for="edd_variable_prices[<?php echo $key; ?>][recurring]">My Sample Setting</label>
				<select name="edd_variable_prices[<?php echo $key; ?>][recurring]" id="edd_variable_prices[<?php echo $key; ?>][recurring]">
				    <option value="no" <?php selected( $recurring, false ); ?>><?php echo esc_attr_e( 'No', 'edd-recurring' ); ?></option>
				    <option value="yes" <?php selected( $recurring, true ); ?>><?php echo esc_attr_e( 'Yes', 'edd-recurring' ); ?></option>
				</select>
			</span>
		</div>
	</div>
	<?php
}
add_action( 'edd_download_price_option_row', 'eddwp_custom_price_option_section', 10, 3 );