Validation Lists - Multiple dependent lists with unique values

Hi there. Long time user of the forum and always found what I need, except this time, hence why i'm posting.

NOTE: You'll likely have to look at the attached to understand what i'm aiming for

I am creating a template to provide quotes for customers. However our contracts have different rates, different job titles etc. So I have a list with columns showing the clients, the different types of deliverable (dayshift, nightshift, etc), then the resource (manager, senior etc), then the units (day/hour), then finally the price.

I would like to create drop down boxes. Initially to choose the client at the top of the page. Then to give a new drop down box giving the different types of deliverable depending on what client was selected. Then the resource depending on what client and what deliverable category was selected, etc. However I can't find an easy way to create dynamic multi-level drop down lists. Pivot tables are no use because after putting the first entry in, I cannot add anymore entries as the reference table has been changed. It can also lead to tables of duplicate entries.

I don't think it's too much to ask of excel, yet i've searched for days with no luck. Is this possible?

Shameless bump.

I had been using the method in the attached file below for multiple dependent lists. However this is not feasible for my application as my table of rates currently has over 2000 rows, with over 50 clients, and lots of other resources and prices. Therefore I'd have to re-order all the rates and add individual columns for everything, which can't be automated as far as I can see.

Credit to http://www.contextures.com/tiptech.html for the below