Setting user rights

Hi,
I'm creating an inventory management tool and need to set edit permissions for users from different warehouses.
I have a table wich holds all the "parts" stored in several warehouses. Each part has a field wich shows it's current location.
For example:
Part 1 - Warehouse A

Part 2 - Warehouse B

etc.
What I need is to prevent users from Warehouse A to be able to edit parts that are in Warehouse B, and so on.

I know how to give permissions with user groups, however, thes permissions are Table based and not "Location" based (Wich is what i need). The only way I found to grant or deny permissions on a record basis is to personalize each user's rights.
Any ideas?
Thanks