Are you talking about the all-in-one style tanks? If so, the tanks themselves are pretty much ready to go right out of the box. You'll need:
- salt
- water
- heater
- live sand
- live rock
All that is available through this site. If you have a decent local fish store (LFS) near you, you can probably get most of it through them as well. For water, I recommend distilled water from the grocery store to get started, but eventually go with RO/DI water.
Once you decide on which tank you want, there are minor tweaks you can do to make them better if you so choose.
If you are talking about doing it all "from scratch", then you'll need:
- a tank
- lights
- pump/power head (for water flow)
- salt
- water
- heater
- live sand
- live rock
Again, most of this is available through this site, and it can also be purchased from most decent LFSs.
Good luck - let us know if you have any specific questions.
