Haven't seen this post active since I first asked, back in March!
In reply to UYD -- the best solution is to create a basic counter with MySQL that holds the same inventory information that your E-junkie inventory uses.
So, if you have 100 QTY in stock on a certain item, you set an item in your own database with 100 QTY.
When a purchase is successfully completed, use an e-mail or success-page response to enter the data into your database, and update the QTY for that item for 99 (-1 from current qty).
You can then query your own database and display that inventory stock qty next to your products. It will be close enough for most purposes.
(I haven't done this, as of yet, but I am quite sure it is feasible! You'd have to have a PHP script as an event handler to update a MySQL DB upon a transaction, in my example.)