starting a saltwater aquarium can be quite expensive. I myself have a 55g, fish only plain set up. i don't have all those gidgets and gazmos on or under my aquarium. yes, i have had all of them in the past and have spent several thousands of dollars on a coral reef. just to house mandarins, tangs, butterflies.
If you don't have the money to spend on the equipment, or fish, you can buy some chromis or damsels, clowns, gobys. they are all hardy and inexpensive species to start your first tank. urchins, crabs, shrimp, snails are fairly inexpensive also, and make a good addition.
as for live rock, you can buy filler rock for the bottom and put your live pieces on the top if you want to, who is going to see the bottom and back anyways. just a suggestion, to save you money.
hopefully this helps you out. good luck.