Order by post meta value gets random results

Why are you using SQL when there is our Codex!

Use this code snippet instead-

function pre_change_query( $wp_query ) {

        $wp_query->set('meta_key', 'package_id');
        $wp_query->set('orderby', 'meta_value');
        $wp_query->set('order', 'DESC'); // or 'ASC'

}

add_filter('pre_get_posts', 'pre_change_query');

$args = array(
    'post_type' => 'estate_agent',
    'posts_per_page'    => 10
);

$my_custom_query = new WP_Query( $args );

See Codex for details: https://codex.wordpress.org/Class_Reference/WP_Query