如何通过嵌套关系Laravel Eloquent来订购集合

Question

Been stuck for a while now even after reading docs & examples. I am trying to get a collection ordered by price. The price attribute is nested in a relation that needs to be accessed by the user ID and the service type ID. Here is the relation between tables in which there is the criteria I need to use for sorting:

EDIT Here is something working thanks to @jarek :-)

$users_available = $users_available->join('stypes_4_user', function($join)use($stype)
                              {
                                $join->on('user_id', '=', 'users.id')
                                      ->where('service_type_id', '=', $stype);
                              })
                            ->orderBy('price', 'desc')->get();

EDIT 2 If you ever end up struggling after using a ->select('*') after the join and not being able to access your model's methods make sure you are calling 'yourtablename.*' and not just '*'. read more here: http://jpcamara.com/selecting-carefully-laravel-joins/