The shock absorber is a bit of a misnomer because the job of the shock is for rebound control, not to actually absorb the shock (that is the job of the spring). If you have a cracked spring, or one that is mis-seated, it will put stress on the shock to actually "absorb" bumps, which is it not designed to do. It is unusual to have three sets fail, so I can certainly buy the broken spring idea.
As for installation, I'd expect at least 2 hours labor along with an alignment fee cost.
2003 Midnight Blue SE AWD w/VDC
Colgan Bra, Mobil One, JWT POP charger
PAC aux input adapter, hardwired Escort Passport x50, KUDA mount for MP3 player, Porterfield R4S brake pads (now Akebono ProACT), ATE Superblue
Yokohama Envigor (much improved over stock Goodyears)
Lots of squeaks and rattles.