Plan on $30 - $50 dollars per gallon. That should get you tank, rock, sand, stand, lights, skimmer, ect. ...
If you can find a good LFS that you can trust and prices are not to bad, you can buy your equipment from them. Always buy tank from LFS since shipping will kill you on a tank.
Other equipment, you might be able to get a better price buying MO (mail)
However, if your LFS's price isn't too much higher, then buy local and SUPPORT them. Paying a little extra can help them maintain quality livestock and equipment.
One more thing, buy as big as you can afford, everyone always wants a bigger tank in long run.
happy reefing