Yes, there is some interesting coding for VBPurchase. One of the biggest problems was the SQL insert of new orders. The base of that problem is where the code uses both $product for the order and then right below it again is another $product containing another array of information about the order.
If you just make the 2nd $product = .. to something like $productinfo = .. then both your arrays of $product and $productinfo will work, and no sql input should be lost... works fine over here.
When the developer mentioned in his description this script should only be used by experienced coders, I believe he really meant it.
Peter