If you take a look at the Nano diaries and pinned topics throughout the Marine section of this forum you'll get a good idea of what is required to set up a SW tank
It is generally recommended that beginners don't go for small tanks as they can be very unforgiving of the smallest mistakes and can cost you the whole tank contents, anything under 30 gallons is generally classed as a 'Nano' so anything larger would be a better idea to start with. There is good reason for this and it's a simple one...........more water volume = more dilution. If you make a mistake then a larger volume of water will 'absorb' the mistake and, if nothing else, give you time to sort it out. A small tank can be totally wiped out within minutes if something goes wrong, like something dies, etc. The basics of setting up a tank remain the same no matter how big the tank: cleanup crew, live rock, fish (maybe), corals (maybe), the cost is the same it's only the quantity that differs...........imagine spending a couple of hundred setting up a tank only to have it all die within minutes because you made a simple newbie mistake
As for the corals you mentioned:
Ricordea florida - These mushrooms tolerate bright light but not direct halide lighting so would do best under T5's. They prefer a good flow of water so powerheads will be required. Not as hardy as standard mushrooms so not generally classed as a beginners coral but are not really that hard to keeo in the right conditions.
Acropora - These corals require very high light levels so Halides are a must to get good growth. They also prefer a fast, random current so Tunze streams or good sized powerheads with rotating heads are a must to get the best out of them. Because of these and other requirements they are not classed as a beginner coral and need an established tank.
Sarcophyton - These corals are usually the first corals people buy along with mushrooms, they do not require any special lighting or current although they generally don't like fast flows. They feed directly from the seawater so are very easy to look after as long as your water is healthy. They are very photoadaptive so the better the lighting the bigger they will grow.
As far as cleanup crews go, anything is fine from 'standard' stock, ie. red hermits, blue hermits, assorted snails and shrimps. Some are better than others but each do their own little part to keeping the reef clean and helathy. A good LFS will be able to point you in the right direction as well as research on the web.
The Tomato clown you mentioned is a hardy fish that is quite often used for cycling tanks. It is semi-agressive but only towards smaller, more docile fish because it is a bit of a bully. These fish do best with fish of similar size (approx. 3" - 4") and temperment but do require a minimum tank size of 30 gallons. They shouldn't be kept with any other clowns apart from one other Tomato if wanted but they must be added together. All clowns are male to start with but one will become dominant and turn into a female. Although most people assume that clowns
need an anenome to live.....they don't and a long tentacled Sacrophyton provides a good home for they with a lot less risk than an anenome brings with it.
As for price tags.............research, trawl the web and find the best price you can
There is no way of saying how much a setup will cost as it all depends on what you're trying to achieve and how you're going to go about doing it.
HTH
