I also first bought a 3.5t trailer for €1600 and then did the BE license for about €700 (minimum hours including fees). Unfortunately, I can’t fully utilize the 3.5t because my Sprinter is only allowed to tow 2t. The trailer already weighs about 300kg, so 1700kg remain. What made me suspicious is that the tax is around €120. The thing just stands around all the time and doesn’t even have an engine, but costs as much as a small car. Insurance is cheap at €40 per year in comparison. So far, as I said, it mostly just stands around because we haven’t started building the house yet. I will use it more often then, e.g., for disposing of construction waste from the GU, wood purchases, or similar. I don’t think it really makes sense for gravel, unless you only need a small amount of material. But for crushed stone/sand/grit, I prefer to have the stuff delivered with a 20/25t.