There are plenty of threads and youtube videos to help you do the job. A helper is a good idea, but not mandatory.
I did not need a spring compressor because there is enough thread to completely decompress the spring on the shock.
First-timers should plan on 2-2.5 hours but a tech who has done this at least one time can do the job in 1.5 hours. If you go the deler route, you should be able to get it installed for about half what your dealer quoted. Did his price include the kit?