Can We Add Live Donor Links To Our Items?

Yes, but keep in mind that it will take the bidders out of the bidding site and into a different browser. 

To add this, go to Items > Manage Items and click on the edit button (or item name) to edit an item. Click on Descriptions & Extras and choose the insert/edit link to create your external link. Be sure to test the link when you're complete. When done editing, tap on Done Editing.