Item Winning Bidder Information can be found under Reports > Event Sales OR  Reports > Sales Data.  

Won By is referring to:

Item Type            Won By

Silent               Top Bid

Silent               Buy Now

Donation         Donation

Quantity          Qty

Live                  Live

Blind                Top Bid

Credit               Blank Cell

Info                  Blank Cell

 Donation, Live, & Quantity. Credit and Info box will be blank on the report.