$params = array_merge(array_keys($goods['cases']),array_keys($goods['unban']));

$sqlFetch = 'SELECT price FROM buy WHERE nickname=? AND paid=1 AND goods NOT IN(%s) LIMIT 1';
$sqlFetch = sprintf($sqlFetch,str_repeat('?,',count($params)-1).'?');

array_unshift($params,$_REQUEST['nickname']);

$stmt = $pdo->prepare($sqlFetch);
$stmt->execute($params);

$price = $stmt->fetch(PDO::FETCH_ASSOC)['price'];