Since you got a smoking deal on it, and seem able to DIY, then I suggest replacing the following. It'll cost you < $200, about a day to do it all, and greatly improve the handling of the car:
and you might as well do struts at the same time.
My car had the same wandering issue at highway speeds, especially on Seattle concrete highways. Similar to tramlining (expected on concrete highways) yet worse. Replacing the steering coupler and FCAB virtually eliminated it.