It depends on the setup you get. You can put one together (equipment-wise) real easy for $150.00 - 200.00.
The following fish that are nano reef safe are located here: http://www.nano-reef.com/fish/
To find a list of soft corals and their ease of keeping, look here: http://www.jlaquatics.com/static/liv...orals-soft.htm
You will be required to do additional research on whatever you select to ensure compatibility, size, etc.
There are a large selection of invertebrates to choose from in saltwater. The snails are awfully pretty. You should see some of these species of shrimp(coral banded shrimp, for example), and there are a number of hermits and crabs also. Brittle starfish are common aquarium scavengers found on the live rock you will buy.
I must advise, when you begin, don't get too excited. Take it slow, patience is key. While it may be difficult to resist, take comfort that the time you wait, will mean the difference between success and an expensive error.
It will be fun, you will have a blast. Good luck.