There are some good images on the internet....it just takes time to search and find them. Just regular image searches for "Marder 1A3" works as well as searching Corbis.com and Getty Images using search words such as "Kosovo German" or "Kosovo tank".
There are for sure images of the Marder 1A3 deployed in the Concord Publications Kosovo book and other various Concord Publications and Tankograd books.
Also, Tankograd released a dedicated book just on the Marder.....Tankograd Military Special 5017 "SPz Marder. The Armoured Infantry Fighting Vehicle of the Modern German Army." There is an entire chapter on the Marder in service.
Here is a review of the book.....