It depends on where you buy it, for alot of stuff.
You'll want about 90-125 pounds of live rock, and it's cheaper to get that online (by a long shot--check etropicals and such for exact prices, but locally you can expect to pay $7/pound an up). You can save--buy about half of that much live, then fill the rest in with base rock (lava or lace rock) that will become active. Ditto for sand.
You'll want some powerheads--I'd use at least 4. Big Al's is cheapest for those, so call it $40-60 there.
A protien skimmer is a good thing to have--usually around $100 will get you a decent one (maybe used).
I'd go with 2 heaters, figure $30 from Big Al's for 2 250-400 watt heaters.
You should check your lights--if you spend big bucks for cool live rock, you want at least 3-4 watts per gallon to keep most of that stuff going.
I'd plan on at least 3-400 bucks, but you can spread it out, not buy everything at once. The gradual approach allows the tank to settle better, IMO. Or, watch the local papers, see if you can find some one who's selling their setup. Happens a lot.