Although the American Government is allowing you to apply for the diversity visa program DV 2011, there will be other charges will apply to you in the last stages.
Visa fee.

A non refundable diversity visa processing fee, and immigrant visa application fee will apply to you. That will be a total of US$ 755 for a single person. If you have dependants, then each of them too must pay the total visa fees even if they are not intending to travel with you.

This visa fees can be paid in local currency or in US Dollars only to the US consulate on the day of your interview.

If for any reason the visa is refused the visa fees will not be returned back to you.

Also there will be Medical Examination fee and Biometric fee for the applicant and his/her dependants. These fee and if there are additional fees related to the visa processing should be paid by the visa applicant.

American government will not provide any assistance for the visa applicant including the air ticket, housing etc.

Don't sell any of your property or valuables till you get the visa.