I have one of those scales that measures your fat and skeletal muscle using impedance (both feet and hands at the same time). These types of scales are not the most accurate, but it's the best I can do for now. I used the same scale before I started up to now so at least I'm hoping the delta is accurate.
I have one of those scales too (only measures feet though) and when I tried it said my body fat was 24%. But as long as you are following the same procedures when measuring, like wet feet, then the change should be ok.
I picked up one of these based on a recommendation of a site I visit. http://www.amazon.com/AccuMeasure-MyoTape-AM-3000-Fitness-Personal/dp/B002VAPHXW
The calipers only come with a single measurement point chart but there are many internet sites that have 3-7 site calculator you can plug your numbers into. May not be perfect but IMO more accurate than most scales. And again if your primarily measuring change it should give consistent results.