<?php
    
$connection = mysqli_connect ("localhost", "shop_user", "12345qwerty", "inet_magaz");   

if (connection == false)
{
    echo 'Не удалось подключится к БД!<br>';
    echo mysqli_connect_error ();
    exit();    
}
$result = mysqli_query($connection, "SELECT * FROM 'products' WHERE 'price' <3000");
if ( mysqli_num_rows($result) == 0)
{
echo 'Товар не найден!';
} else
{?>
	<ul>
		<?php
		     while ( ($cat = mysqli_fetch_assoc($result)) )
		     {
		     	echo '<li>' . $cat['tittle']. '</li>';
		     }
        ?>
    </ul>
 <?php  
 }
 ?>

 <?php
    mysqli_close($connection); 
?>