Having mastered the 'standards' of each 'Land' in peacetime, I became fascinated by the 'Ersatz' of mobilisation. This obviously complicates things a great deal, and you have to distinguish between period equipment and contemporary knock-offs.
In France, your Entlisted helmet will sell for between €1,200 and €1,500. The original drilling for the Lion Hessois is a plus, but the lack of regimentation is a minus.
The artillery officer's helmet is rare and correct (no star for Hessian officers before the war). From the inside, it looks to me to be made of Vulkanfiber, and with a high ball, a poor quality sweatband, and red and green waxed canvas, this is a helmet made at the start of the war. The silk cape is missing. In France around €2,000-€2,500.
These are prices "between collectors", on forums, or "at the hammer" in auction rooms. For dealers such as Weitze, add €500.