maching item from main data tab and picking correct $ amount

I am creating inventory count sheet
I have all items on one sheet - and multiple tabs for different places where counts are done
so if I go to one of the tabs and enter vendor and item number I can use index and mach 2 criteria array formula to find the item name from the main data sheet
so now each item has two counting units option, (like case and smaller count unit) with associated $ amount
on my counting sheet I want only to pick one counting unit, how can I say - if I find the item - mach counting unit for this item to the price on the main tab

a b c d e f g
vendor item# name case $ for case bottle $ price for bottle

my problem is that I have large range of different counting units in column d as well as for column f
I might put them down to 10 -12 and have list to choose from for counting unit, but how to find the item (index and mach) and than based on counting unit choose colum e or g
and I dont want to have 2 unit count options, since I can see the problem were counts will be entered in the wrong column

thanks

Thanks - so I want to pick up in column I counting unit, and that base on that unit to pick up cost from sheet1

it does pick up but if I change unit counted on PM tab, it does not change $ amount, I need to be updating sheet1 values, and have it updated for value in unit counted on other tabs
I have only one counting unit as example, but I will have other tabs with different items, or just couple of them
also if I change unit counted on pm tab and I don't have that unit for that item on main sheet1 I need it to give me error and recognize it is not available

column D and E are perfect, but I is not what I am looking for, In I there should be drop list maybe ( I know how to do this) so if I choose lb or case lets say for lobster I need price in J to change with formula
Sorry for not answering before, I was out with flu

Help please

This is what I came up with, and it works, up to last part - where if I change unit on pm sheet for item, it does not give me correct price but N/A

=IF(INDEX(Sheet1!$H:$H,MATCH(1,($A8=Sheet1!$A:$A)*($B8=Sheet1!$B:$B),0))="","",IF(INDEX(Sheet1!$J:$J,MATCH(1,($A8=Sheet1!$A:$A)*($B8=Sheet1!$B:$B)*($I8=Sheet1!$J:$J),0))=I8,INDEX(Sheet1!$K:$K,MATCH(1,($A8=Sheet1!$A:$A)*($B8=Sheet1!$B:$B)*($I8=Sheet1!$J:$J),0)),INDEX(Sheet1!$M:$M,MATCH(1,($A8=Sheet1!$A:$A)*($B8=Sheet1!$B:$B),0))))

bit of I only have last part = INDEX(Sheet1!$M:$M,MATCH(1,($A8=Sheet1!$A:$A)*($B8=Sheet1!$B:$B),0) it does give me correct price, so it is somewhere in the formula conflict and I just cannot figure it out

Post an updated file: I assume you have a drop down to change unit?