Passing Custom Field Values inside Shortcode

Okay below you will see my first attempt at a shortcode. What I am trying to do is call in a list of custom posts (named “ulisting”). Instead of a normal URL to take you to a single-instance of the post type, I want to throw in a custom field value. However, the custom field doesn’t seem to display. What am I doing wrong?

function customPostType_shortcode($atts) {
	extract(shortcode_atts(array(
        'type' => '',
        'limit' => '10',
		'ucategory' => '',
        ),$atts));

        //The Query
    query_posts('post_type=ulisting&posts_per_page='.$limit.'&user-type='.$ucategory.'&orderby=title&order=ASC');

		echo	"<div id=\"members-dir-list\" class=\"members dir-list\">";
		echo	"<ul id=\"members-list\" class=\"item-list\">";
        //The Loop
       if ( have_posts() ) : while ( have_posts() ) : the_post();

                echo  '<li>
			<div class="item-avatar">
				<a href="http://webpages.leeu.edu/'; echo get_post_meta($post->ID, "username", true); echo '"><img src="http://www.gravatar.com/avatar/09c326816694a26d129bd1c2f90c4b36?s=50" alt="Member avatar" class="avatar user-1331-avatar" width="50" height="50" /></a>
			</div> 

			<div class="item">
				<div class="item-title">
					<a href="'; echo get_post_meta($post->ID, "username", true); echo '">'; echo the_title(); echo '</a><br />
                    <span class="update">'; echo the_content(); '</span>
				</div> 

			</div> 

			<div class="action"></div>
			<div class="clear"></div>
		</li>';
        endwhile; else:
    endif;

        //Reset Query
    wp_reset_query();

		echo	"</ul>";
		echo	"</div>";
}
add_shortcode('usersList', 'customPostType_shortcode');