Updating a cell over internet

I know it is possible to update a cell over the internet. Here is what I want to do, and maybe (with some expert help) we can achieve it!

I have some end users whom are selling products.

They have a price sheet on a workbook

I want to add a button that when clicked will access a "master copy" or stored data, and return with the new prices!

Please help if you know a way!