Don't listen to oromis, he's obviously never played it.
You need $0 to play D&D. You just need to find a group of people to play with. One of the players has to have the core books, an adventure, a play mat, and miniatures(optional). If no one in your group has good experiencing DMing, you may want to stick with pre-made adventures. They sell books with a variety of campaigns and I'm sure there are free ones online. If everyone is new you should switch up DM every so often so everyone gets a feel for it. All the costs for the books and other materials can be split between the players as you only need one copy of the core books.
4th Edition has been very streamlined to make it appealing to new players. The rules for character creation are very simple and are explained n the Player's Handbook.
The most difficult part of playing D&D(and every tabletop game) is finding a good group that meets consistently.
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