I've just uploaded a new version of my RedBubble art manager application (this is v18.104.22.168). You can get it from here.
This release makes a change to the work promotion dialog that lets you specify where you want the promotion code to link to. Before it would only link to the normal view page for a work. Now, as an option, you can link directly to the purchase page for the work:
The difference is as follows. If you click on the following image you'll get the normal view page:
whereas with the promotion code set to link to the buy page, you'll get this:
Before anyone asks: no, sorry, I can't have it so that you can specify exactly which product is linked to when going to the buy page.