There is no point doing it. You're lucky if recovered gold covers the cost of chemicals. Then you need to work with those dangerous chemicals, a lot of time wasted for nothing. In the end you end up with a little bit of gold and a lot of dangerous chemicals you need to dispose. Those who buy electronic scrap for gold recovery on ebay are idiots. In the end, unless you do it at industrial scale, there is no point. All you do is waste your time, put your health in danger and pollute environment.