If the only D-Specs you can afford are used, pass. They are a wear item.
You choose your struts based on the springs you plan to use. Of the three you listed, I would probably go the Koni Insert route, if it were my car.
From a performance standpoint, you can't beat RCE or the Swift Spec-R springs. For a bit milder spring rates, Epic, SPT Pinks, Swift Sports, or STI takeoffs. RCE and Swift are the only two companies I know of that make wagon-specific springs. Figure how aggressive you want of a spring rate, then decide based on drop.
Group-N tophats are a good buy, but upgrade the front to the Whiteline Com-C mounts (if that means sacrificing the rear for a regular OE one, it's worth it).
The only coilovers of the ones you mentioned I'd bother considering would be the STs. Other cost-effective coils you could look at would be Feal.