First figure out what type of tank you want, Fish Only will be the cheapest. For a Reef System you definetly need a Skimmer and very expensive lighting.
It will cost ya about 550-600 dollars to start that size tank up. It's not just the equipment it's the LiveRock that will run ya about $250 alone for you tank. 1.5lb/gal of water. Add Some Live Sand in and your up to about $300-$350 depending on if you use playsand on the bottom.
I would use an Emperor 400 for fish only for carbon filtering or go with a skilter. then 2 powerheads for water movement, Salt, Heater, Thermometer, Hydrometer or Refractometer, Test Kits and a Good book.
Plus alot of patcience, after the tank is set up, it will take up to 8 weeks to cycle the tank before you can put fish in. Also the fish rule is 1" of adult fish length per 5gal of water. So your in the 9 inch area.
Hope that helps ya out, I recomend getting the book titled The Conscientious Marine Aquarists ...it'll provide a good foundation of information to get you started.