Updating average cost and qty on hand for weekly shipments in excel 2007 inventory sheet

Hello , I am trying to get two cells to be used to adjust other cells on the same sheet repeated times.
In a inventory sheet I have 5 columns as such , A1 previous balance, B1 Qty received, C1 qty on hand, D1 last cost, E1 current avg cost
What I want, is to be able to enter my weekly received items in the B1 Qty received and the new cost in D1 Last cost cells and have them calculate my current average E1 and update my qty on hand C1 total. This in itself is not the biggest challenge. I was asking if there is a way that after the E1 current average cost and C1 qty on hand are updated by that formula, that the next time I enter a new B1 qty received and new cost in D1 Last cost cell they will update again basically without changing the earlier calculations achieved .
Example: Today I have item X with a A1 previous balance of 10 , with a D1 last cost of $1, and E1 current avg cost $1

I want to receive B1 10 more today at $.50 D1 last cost, which ideally would end up showing

A1 previous 10 (or 20 if adding) , C1 Qty on hand 20, D1 Last cost .5, E1 current avg $.75

Next week I want to receive B1 10 more at $.25 D1 last cost , which then would update showing

A1 previous balance 10 (or 30 if adding), Qty on hand 30, Last cost $.25 and E1 current avg $.58

Any help would be greatly appreciated. I am using 2007 excel and have very limited experience but have always tried to learn as much as I can. Thanks in advance.

I didn't get $.58 like you. I've attached my results. If you could attach a file showing exactly you need that would help.

averageCost.xlsx

Thanks for that input the difference is that I only received 10 @ $.75 and another 10 @ $.25 for a total of 30 on hand at the end. Either way that works, but since I am using this on an inventory list is there a way to keep it all on one row? The way yours does this makes multiple rows for each item and I am trying to keep it on one line per item, basically updating the cells rather than creating a new cell or row for each delivery. My inventory can range up to 4000 items. Thanks again, but I may be asking for something that cant be done.
I was able to do it by making a column for rec 1, rec 2, rec 3, and another column for new cost 1, new cost 2, new cost 3 etc. they then can be entered and will average out in the current average column with another formula. The problem is some items I receive 2 times a year others 12 times or more.

I tried to upload a sample of my sheet but it wont upload. I will try Saturday when I get home from work.

I attached a form I am using now to achieve as close to what I need as I could make. This is one way I am able to keep the info on one row , while updating the current average cost and qty on hand as we receive product. The restriction I have is the need for multiple columns for each delivery Qty and cost. This is why I was looking for a way for a single cell to be used to enter my new cost and a single cell to enter my qty received, that would update the newest figures.
Any help or ideas would be great.

If I understand what you're saying, you want the ability to get a new average cost with the data you input, using only one cell or a limited amount of cells over and over again. Am I correct in my assumption?

Yes exactly. Right now if I use one cell for qty received it will calculate the new current on hand qty, but the next time I go to enter the next shipment as qty received it replaces the last qty received not adding to it. If that makes sense.
Basically I would like the qty received and new cost column to just be used for the calculation process and be able to be used again for the next shipment always updating the new current balance and new qty on hand.