FWIW, "Transactions" (the "TR" button in IN-A) do not get archived. There's a lot more info to wade through, but (some of) the info is there.
 
On a related note, I posted a question yesterday about printing Archived Invoices, just because of this situation. The shipment in question had its' invoice archived and I needed to know the price we charged. Transactions gave me the Date, Invoice #, Cost, but not price (I guess I could edit the grid...?). Since I couldn't figure out how to print Archived Invoices I ended up looking at my PDFs (we do a monthly Invoice Print of all invoices into a PDF file, along with a bunch of other stuff). It wasn't too hard since I had the date so I could pull the right month, and the number so I could do a quick search. But it would have been a lot simpler if I had that right in IN-A.

We are working on the option to look at archived invoices, PO's, Work Orders in IN-A.  Close, coming soon....