$args = array( 
	'orderby' => 'title',
	'posts_per_page'	=> -1,
	'meta_query' => array(
		'relation'		=> 'AND',
		'availability_key' => array(
			'key'		=> 'availability',
			'value'		=> '1'
		),
		'price' => array(
			'key'		=> 'start_price'	
		),
		'dateavailable' => array(
			'key'		=> 'date_available'	
		)
	),
	'orderby' => array(
		$sortby => 'ASC'
    ),
	'post_type' => 'floorplans'
);

$the_query = new WP_Query($args);