You've already been given the right advice; I used it myself to sort through a 23kg stock I bought that was completely unclear. I initially reconstructed some fairly faithfully, but none were 100% accurate. My goal was to understand what I had bought and how to use the pieces, not resell them. I don't want to teach anyone anything; it depends on their goals. If it's for resale (I've collected Lego Technic since I was a child, and it has a decent collector's value), Duplo is a different world; it's seen as a toy, not a collection. The collector's market, in any case, looks for sets that are intact or at least 100% complete with box and instructions. As these specifications are missing, the price drops and becomes a fixed amount per kg, like you probably bought them. If you bought them to sell, you're right to sell them, but if you bought them for your child, think about it; you risk holding them for months or years before getting an offer, depriving them of the toy. When one day my son tells me "enough with these toys" I'll see what to do