No longer valid - EE3 now supports this in the Template options.

event_espresso_price_range.php

<?php
//This function should be added to the custom files addon, in the wp-content/uploads/espresso/custom_functions.php file, or your in your theme, in the wp-content/themes/theme-name/functions.php.
function espresso_price_range($event_id, $text = '&mdash;') {
    global $wpdb, $org_options;
	$result = array("max" => 0, "min" => 0);
	if (function_exists('espresso_members_version') && is_user_logged_in()) {
		$price_field = "member_price";
	} else {
		$price_field = "event_cost";
	}
        
	$sql = "SELECT MIN(ep.{$price_field}) AS min_price, MAX(ep.{$price_field}) AS max_price FROM " . EVENTS_PRICES_TABLE . " ep INNER JOIN " . EVENTS_PRICES_TABLE . " ep2 ON ep.event_id = ep2.event_id WHERE ep2.event_id = $event_id ";
	$price_row = $wpdb->get_row($sql);    
        
	if ($price_row !== NULL) {
		$result['min'] = $price_row->min_price;
		$result['max'] = $price_row->max_price;
	} else {
		echo $org_options['currency_symbol'].'0.00';
		return;	
	}
		
	if ($result['min'] == $result['max']) {
		$result = $org_options['currency_symbol'].$result['min'];
	} else {
		$result = $org_options['currency_symbol'].$result['min'] . " $text " . $org_options['currency_symbol'].$result['max'];
	}
        
	echo $result;
}
add_action('action_hook_espresso_price_range', 'espresso_price_range', 20, 2);

event_list_display.php

//Just add this line of code wherever you want the price range to display (most likely in your wp-content/uploads/espresso/templates/event_list_display.php file):
 
<?php do_action('action_hook_espresso_price_range', $event_id);?>

//Example:

<p id="p_event_price-<?php echo $event_id ?>" class="event_price"><span class="section-title"><?php  echo __('Price: ', 'event_espresso'); ?></span> <?php do_action('action_hook_espresso_price_range', $event_id); ?></p>