Set default values for a field from a node In Drupal, when you create a field, you can specify the default value for a field.
For example, if you have a field called price, you can set the default value to be 400.
When the user creates a new node, 400 is the default value, but s/he can change it to whatever s/he wants. 

Is there a way to link this default value to a node field value.

For example, lets say on node/12 I have a field called "price default". If the user enters 500 on this field (on node/12), the default value of the price field (for all new nodes) will change from 400 to 500.
Ahmed was close, but to take it all the way you need to fetch the field's value:

function MODULENAME_form_alter(&amp;$form, $form_state, $form_id) {  
  if ($form_id = 'YOUR_FORM_ID_HERE') {
    // Fetch node that has default value
    $node = node_load($nid);
    // Fetch the value from price field
    $node_wrapper = entity_metadata_wrapper('node', $node);
    $field_val = $node_wrapper-&gt;field_price-&gt;value();
    // Set fetched value as default
    $form['field_price'][LANGUAGE_NONE][0]["value"]['#default_value'] = $field_val;
  }
}



I am itching for a clean way to avoid having ['und'][0] in there,  as these values can change with localisation, but this would still work.