Another way to do this is to add "site:commons.wikimedia.org" to the end of the Google search query. (This also works in DuckDuckGo, my preferred search engine.) I couldn't find any image results for "Trump turd face", but I found plenty of caricatures using the search string "Trump caricature site:commons.wikimedia.org".

Re paid images, Alamy.com is another choice that may be less expensive than Getty. FWIW, I used to host some images with them, but I got pissed off and left when I found a bunch of my public domain images* on their site being sold by another photographer without disclosure of their free license status. (I found those same images being sold on Getty as well.) Selling public domain images without permission or attribution is perfectly legal, but profiting off them in this fashion is ethically dubious IMO.

* Taken in the course of my work for the City of San Francisco. My other recent images are CC licensed, not public domain.