Why are you buying the AT875? Are you going to be able to swing the boom yourself, or do you have someone semi-reliable to do that for you? Otherwise a shotgun mic may be the entirely wrong choice.
Please list all the audio gear that you currently have plus your camera make/model with pertinent audio details. Oh, what are you going to be shooting (narrative or documentary) and where (indoors [what types of rooms] or outdoors [where? urban, rural?]). What type of human audio help will you have? And the most important question... What's your budget?
For the meantime, here's my $1,200 buying guide.
Shotgun mic kits will have the shotgun mic, boom-pole, shock-mount and simple wind protection (softie).