Thank you very much for your post.
As mentioned in our email conversation, we are planning for stock value reporting feature.
Exporting your products with their related purchase price should be possible using any exporting tool as pp is a meta key.
Value of your stock depends on what you are doing - if you are just making products to order from BOM (this is related to our Product Levels premium addon), the value of your inventory should only be calculated from BOM.
We will consider this when creating the widget for our Dashboard after the large 1.5 ATUM update is out.
Yes, as you said, the BOM options are very variable and complex. I can just give you an example of what we need to achieve in the next Product Level upgrades:
Imagine you need to show stock amount in the front end that is calculated according to the amount of BOM you have. However, you use BOM A to make 10 products and even to make another 5 different BOM. There is a BOM B that you need to make BOM A. See how complex this could get? And I have just started as it could go even deeper.