Linking 2 Sheets With SUMIF Function

I am trying to link 2 excel sheets together and I am wondering if using the SUMIF Function is the best way to do this. I will try to explain and illustrate my position.

First I have a sheet called Master where I import my companies inventory and prices. It contains ALL our inventory. Looks like this:

(Column A) (Column B)
(Item Code (Item Price
(ROW1) THUMBRID $5.00
(ROW2) THUMTUBE $2.00
(ROW3) ZPIN $0.30
Now this master sheet is changing all the time as we import new products and prices all the time. So, this is a "list" where I can sort it by Item Code alphabetically.

Now, I am trying to make another worksheet with a list of what each of our kits contain and there prices. I will call this ThumbPiano. Like this:

Column A: COLUMN B:
THUMBRID $5.00
THUMTUBE $2.00

We have many different kits, that only take a couple of products, and our inventory list is at like 3,400. I want to be able to go into the Master sheet and update an Item price and have it automatically update it in whatever worksheet contains those items. But how can I do this if I add an item into the workseet. Then the cells move and whatever data was in that cell before is not there now.

So, that is why I chose the SUMIF function. Maybe there is a better one? Here's what I tried...assuming the two lists before, and the code Zpin is extra in the Inventory list because we do not use it in the thumb piano hardware pack.

I tried:
=SUMIF([Master.xls]Sheet1!$A$1:$A$3,A1:A2,[Master.xls]Sheet1!$B$1:$B$3)

It works, but then when I save it and close out of it and then re-open the ThumbPiano sheet it asks me if I want to update the sheet. I click yes, and then all the cell says "#VALUE!" "A value used in the formula is of the wrong data type." Please let me know what is going wrong. I know there has to be a way to do this. I just wonder if the SUMIF formula is not the way to link 2 sheets together...but if it isn't please keep in mind that I have this looking through 3,400 parts and I will be adding to them all the time, so it needs to search through all those parts and display the correct price....