Rear Springs - Which Ones Should I Buy?

I'd suggest that you survey a few other shops in the area, get a good cross section of prices.

For an experienced mechanic this should be a 3~4+/- hr job.

I just changed my springs on a similar car. Only difference was mine is a Nevada car, yours is an Illinois car. EVERYTHING on the underside of your car will be corroded or rusted if it has seen a winter in Illinois. You will need an impact wrench, and possibly a torch to apply heat to break a lot of the fasteners loose. Some of them may even break whiole trying to loosen or tighten them which could require an extractor (like mine did on the rear shackle mount) This will be a pretty complicated process, although not impossible, without the right tools. So if this is your primary mode of transportation, I'd suggest it be turned over to a shop who is equipped with items to fix the unexpected.

Have you consider a leaf spring or suspension shop in Chicago, rather than a general mechanic?