I also searched for a way to export my existing 'products' in a way so that I could easily update things and re-import them as described here. After a futile attempt at finding nothing this is what I did:
1) I created a 'View' for all nodes of 'type product' and defined my fields for display as: SKU, Stock Level, Sell Price, List Price.
2) I made the 'View' display as a table and in seconds I had a lovely list of everything the way I wanted it.
3) Copy, Paste, Change in Excel (or whatever program you want to use)...
Now, after changing all things to the way I want them, I am hoping this will just upload easily as described here and all will fly according to the SKU!
I hope that helps you.