Diploma Mills - Beware!
Ever heard the saying "If it sounds too good to be true, it probably is?" This saying definitely applies to high school diploma programs! Real high school diplomas -- the ones that will get you a better job or get you into college -- take some real effort.
If you find a school willing to sell you a high school diploma for, say, $400, you can be pretty sure that they are selling you a piece of paper with "Diploma" written on it. Colleges and employers won't accept it - and, yes, they do check! That's an expensive piece of paper.
The U.S. Department of Education has posted a number of resources to help you figure out whether a diploma program is legitimate. Check this link out.
You also need to watch out for bogus accrediting agencies. In the United States, accrediting associations must apply and be evaluated by the US federal government. You should look for accrediting bodies that are considered a legitimate component of the U.S. education system.