The cost of a greencard can range from no charge at all up to many thousands of dollars, depending on a number of factors. Some immigrants may need to hire an attorney who specializes in immigration law if they are denied a visa for a specific reason, and some may pay for help getting a visa from a company, but for most immigrants there is a free visa option. You can find a lot of information on http://www.green-card.com/. One of the least expensive methods used is the diversity lottery program, operated by the US State Department. There is no cost to apply for this free green card program, but the application must be submitted in electronic format to the State Department website during the annual registration period.
There are some unscrupulous companies that promise to help complete the application so that the applicant has a better chance of receiving a greencard, but these companies are a fraud, and simply take money without offering real results. The visa lottery is an annual event, and a pool of applicants who are qualified for the program is used to give out the fifty thousand visas allowed under the program regulations. There are no family, employment, or education requirements to meet that other visa programs have, and any immigrant from an eligible country who meets the program guidelines can apply.
The green card lottery offers immigrants who are under represented in the USA an opportunity to be chosen for a free green card, based on the region of their home country. Not all immigrants are eligible, because anyone who comes from a country which has had fifty thousand immigrants to the US in the previous five year period is not eligible because of this. The goal of the program is to allow a diverse group of immigrants from all over the world an opportunity to come to the USA and gain permanent resident status.

