Travelers looking to take a tour on Easter Island can either make their arrangements on the mainland, or on the island itself in Hanga Roa. Keep in mind, however, that tour operators based in the mainland are likely to be more expensive, unless you are with a larger group.
The length of your tour is up to you, as packages range from day tours to week-long endeavors. Tours will take you through fascinating archaeological sites like the Orongo ceremonial ruins or the lines of Moai. If history's not your thing, you can also go volcano trekking or scuba diving. Tour prices depend on the level of luxury, but most are pretty high, especially since the majority do not include airfare, which is usually about $800 from Santiago.
If booked locally, a simple four-day tour with transportation, meals, accommodation, bilingual guide and entrance to the national park starts at $285 per person; a seven-day tour should be in the $800-$900 range.
Here are some related tips to help plan your trip to Chile: When to Go: La Serena, Chile Mail, Shipping and Customs, Maps, Officialdom and Business in Chile, When to go, Southern Patagonia & Tierra del Fuego Border Crossings, Carretera Austral and Northern Patagonia Border Crossings, Services, Working in Chile and Chile's National Parks.