Selecting from filter list to generate a total??

Hello everyone!

I'm relly sorry if the question I am posting is a trivial one but Excel is like a different language to me and I am trying to blunder through! So my question will probably not even make that much sense.

So I am trying to make a supply list for my work where I can calculate how much money is needed for supplies. It has all worked so far except for two things.
1. I would like a drop down menu/filter on only some of my coloumns but can only seem to create them with autofilter which does them on everything. Is there a way around this?
2. After my grand total I would like to be able to calculate a total from the subtotals that come up with a particular filter. So I would like Auto filters for my SUPPLIER, CATEGORY and FOR coloumns and then be able to pick a filter from all of those combined in a seperate section of my worksheet which would then calculate the total for that filter.

So in my attached example, I would like to sort how much money I will be spending at muji, so in L5 I would like to be able to select Muji (or a category, or a name from the FOR coloumn) and have the total amount for everything I am buying at Muji displayed in L6.

Is this possible? Am I being silly and longwinded? Any help would be much appreciated.

Thank you.

Supply List.xls

no takers?