Module to edit field data on multiple instances/nodes (in bulk) I've a need to allow my client to easily edit the price field for the projects (content type). In total there're about 1.5k nodes and he wants to change the price once and that it would be applied to all the 1.5k projects/nodes.

Is there a way to do it using some of the existing modules in an easy way, so that an amateur could make the change? Or can it be achieved by custom module, if so could you give some instructions in terms of how should it be done programatically?

I'm not a developer, but will pass it to my colleague, who's a developer. He tried to code a custom module, but it takes about 18min to update the field data for 1.5k nodes... So apparently something is not right.

Thanks.
For Drupal 7 you will need views bulk operations which packages this and other bulk operations.  For Drupal 8 you need Bulk Update Fields 

Below the procedure is for Drupal 8 but very similar for Drupal 7

Install the module and modify the Admin content view found by going to admin/structure/views/view/content or perhaps you can use any view that you want.

add field and search for Node operations bulk form to add and make sure you enable 

Selected actions: Bulk Update Fields to Another Value

With this when on the view page you can select 1 or more nodes and modify fields in bulk