1) Live Rock is generally between $5-$7 per lb if you don't want to chance stuff that has been in someone else's tank and you generally want 1-1.5lbs of live rock per gallon of tank. You can buy a bunch of dry rock with minimal live to keep costs down but it takes much longer to cycle to the tank, so be prepared to spend a long time cycling. With all live rock it generally takes 4-6 weeks to cycle (possibly more)
2) You will probably want live sand as well, once again about 1lb for every gallon of tank. It generally runs about $1 per pound
3) You will need a tank heater that fits your size tank and specifically mentions it is for marine setups. Figure $40-$50 for your size tank.
4) You will need a couple of power heads for your size of tank and they will probably need to be in the 1950 gallon per hour range if you want to keep things well circulated and give your corals good flow. These will run $70-$80 each if you go with the Hydor Koralia line (probably the best bang for buck power heads out there). You will also want to use them during the cycling process.
5) With corals there is a ton of variation in the needs and requirements. Some are as simple as putting coral glue on them and attaching them to the top of your live rock in an area where they will get plenty of light and current flow from your powerhead. Others actually need some kind of vitamin type supplements and very specific lighting and water quality requirements. Personally for me there is no coral on the planet cool enough for me to have to spend more time on than my fish. If it isn't a super easy to deal with coral, I don't want it in my tank.
6) Filtration. There are generally 3 types of conventional filtration: HOB (Hang On Back), Canister Filtration, Sump. A Sump is generally made from a secondary smaller fish tank or even a rubbermaid container depending on what size you want to go with and then you would put your filtration equipment in there and can have live rock in there as well. If you can do it yourself you can make a good size one for $100-$150 plus the cost of adding a filter. A Canister filter for your tank would generally be in the $200-$300 range and honestly for saltwater tanks are THE WORST OPTION. They are very prone to nitrate build up, leaking and are a pain to clean. HOB or Hang On Back Filters are very cost effective. You could get a Fluval 110 for $80 or less from petsmart and it should work fine for your tank provided you ditch all but the stock carbon filter bag and go with the likes of a Chemipure media bag. That said, you won't use the Chemipure until after cycling the tank and it might be wise to just get some form of basic carbon power filter to use during cycling.
7) Saltwater. You can get your own RO or RODI system to produce your own and then mix the likes of Instant Ocean salt in it or you can get a bunch of 5 gallon jugs and buy premix from your local saltwater fish store. With saltwater fish especially, I cannot stress enough that even de-chlorinated tap water is not fit for saltwater fish and will give you incessant algae problems at best. It is generally more expensive in the long run to buy it from the fish store, but the advantage is that you don't have to go through the hassle of running the system yourself or getting the salt mix wrong. Generally 1.025 is considered the best balance between fish and corals, so most stores will run at that. A decent RODI system will run you $150 and you will need to have a rolling garbage can to keep the RODI water and even the best system will produce 3-4 gallons of waste water for every good gallon of RODI water, so you will need to figure out what you want to do with the waste water. Local Fish Stores usually sell the premix for about 75 cents to $1 per gallon.
Obviously there is more equipment you will need before you can add fish and corals (ie Protein Skimmer), but the above should get the tank cycling.
