<?php
/**
 * Hide single item price display for non-logged in users
 *
 * @param     string $display_price
 */
function acme_single_item_price_display( $display_price ) {
    // Get WPD settings from General tab.
    $wpdas_general = get_option( 'wpdas_general' );

    // Check if user is required to be logged in to shop.
    if ( isset( $wpdas_general['wpd_ecommerce_cart_require_login_to_shop'] ) ) {
        $login_to_shop = $wpdas_general['wpd_ecommerce_cart_require_login_to_shop'];
    } else {
        $login_to_shop = NULL;
    }

    // Hide price if user is required to be logged in to shop.
    if ( ! is_user_logged_in() && 'on' == $login_to_shop ) {
        $display_price = '';
    } else {
        $display_price = $display_price;
    }

    return $display_price;
}
add_filter( 'wpd_ecommerce_single_item_price', 'acme_single_item_price_display' );