Hi there
This will depend on your merchant program. They will either want a csv file or a php file to run for themselves.
If they want a php file than all you need to do is send them the URL eg
http://your-doamin.com/shop/getprice.php.
If they want a csv file then you need to out put the results of php file above to a file directly and then sen them a URL to that file. If you don't know how to write the result of the php file to a csv file then post again and I'll post the code for you.