Tires, shocks and struts. Occasionally a water pump for the older ones.
The electronics aren't the greatest, but 99% of the time the only issues are a worn or broken sensor on the newer cars. 1983 only cars [and at that, mostly wagons] had terrible wiring, it literally falls apart on every '83. '86+ had a VSS and electric speedo, the earlier models had cables which die from time to time.
All in all, they're pretty durable machines.
As far as sub-$1k coilovers, bolt-in you're dreaming. There's still some fab-work involved, but the parts themselves can be had for under $800.
<<< Go there for anything suspension related for a 200-series chassis. Ben is a genius when it comes to suspension design for these cars. While his stuff is mainly performance-oriented, he can also engineer some things to get you unibody-scraping low, and it'll last. I'm taking the road-less-traveled with my '79 242 and am building my own suspension setup, though I am building it along the lines of Kaplhenke's stuff.
If you do go with anything Kaplhenke, be sure to tell them a friend of Jim Schardt @ Clockwork Calibrations in Albuquerque referred you.