Looking for Sources to Buy International Mixed Lots

In the past I have bought lots of stamps through second hand websites. In some cases it was the so called "kiloware". This is a box with all kind of stamps but instead of describing the content they just post the weight off the box. In my opinion you end up with a lot off duplicates which just pile up at my home.

Another thing I sometimes do is too buy stockbooks or albums at yard sales or internet sales. They are usually better and at least it has a better overview of what the content is.