Accessing "purchase price" and "sale price"

We use NSSB, so we have limited (aka none) access to scripting and ODBC, but here goes.

We need to access the "purchase price" value of an item, and the "sale price" in order to determine our current margins based on the cost price of an item and the current price list sale price.  The majority of our items are drop ship, are usually purchased in USD and are sold in either USD OR AUD.

When we attempt to include "purchase price" in a report or search, it provides the value of the purchase price as at the last time the item record was updated, in AUD.  This figure is one that I would normally have related to the last purchase price.  This makes it useless to perform any margin analysis because the values are all costed at different times.