granted that i'm here in Japan where everything costs more, but i only have a 40 gallon that i spent about $700 for the initial set up.
hood (all glass tops)
lights (only a two light system-each light only 37w)
crushed coral (sand is usually preferred)
one thermometer (i now have 3)
stand (plain black iron stand)
canister filter (japanese brand)
since then, i have had to purchase
2 powerheads (approx $50)
2 more thermometers (approx $3)
salt (two bags already each bag approx $30)
test kit (approx $10)
live rock (approx $100-not even half of what is recommended)
all this is just equipment, you really have to keep in mind that there is more equipment recommended. you will need a skimmer which could easily cost a couple hundred dollars for a tank that size, and you will also need a much better light source than what i have. i agree with trotty, easily over $4,000. good luck though and don't forget us when you do finally set it up.