You don't mention whether you already have these, but you must consider their costs as well:
1. A tripod. A good, steady tripod that wont wobble in the breeze when you open the shutter for 1/2 a second or longer.
2. A dark cloth.
3. A meter. For tranny work, I would recommend a spot meter.
4. Grads. for landscape work with tranny film, I believe they are a must-have. Otherwise, shoot on reversal film.
5. Film holders.
6. A changing bag (or darkroom) to load up and empty the film holders.
7. A decent bag to lug everything around in.
8. Film (!). If you plan on going on a longish trip, readloads/quickloads are convienient, take up less space & are less liable to dust spots. On the downside you'll need a holder (the polaroid one works fine) and the film is more expensive than sheets.
9. Somewhere to process film. In the long run, doing it yourself is cheaper with a Jobo processor, but if you know a lab you trust who'll process 5x4 in E6 then use them.
10. A cable release & spare.
11. A loupe. If you are blessed with perfect vision and can compose on the ground glass at F32 them lucky you. If you are a normal human, you'll need a loupe! an old 50mm lens from a 35mm camera works fine.
12. Time. Lots of it! You can't rush LF. If I've scouted out a location, know exactly what lens, movements film etc I'm going to use I would be pleased if I set-up, shot & packed up in under 30 minutes. That doesn't include waiting for the sun to come out (or go in!), the wind to die down etc.