Chris,
To replace the rear springs should be no more than 15 minutes per side. The bottom retainer for the spring comes off, and the shock needs to be disconnected at the bottom. Spring pops right out.
Another option is Espo for the springs. I bought from them based on several recommendations on this forum, and am pretty happy with the ride height, even with many pieces still to go in. I think it cost around $90 to my door from Espo, which is in PA.
Mark