Calculating Body Fat %

Ok, a week or so ago I saw the movie, "Supersize me," where a guy eats nothing but McDonald's for a month. When he started, he was 6'2, 185#, and had a body fat % of about 11%. When he finished, he was still 6'2", but about 215#, body fat 18%. This got me thinking about my own body fat (and also more about what I eat). So other than going to a special doctor or whatever and paying a huge amount of money, does anyone know an easier way to calculate your body fat? I found this calculator through Google: www.he.net/.../prothd2.html However, I think it is being too generous for me (body fat about 9%). I did find this one too: www.linear-software.com/online.html It seems that the caliper method is the most accurate. Has anyone done this, what was the cost?? Thanks.