A high-quality stainless-steel anchor should cost around 3-5 times more than a standard galvanised anchor. Stainless steel varies in quality and an anchor that simply states it is stainless steel may not mean it reaches the high quality standards you would expect.
If you construct a stainless steel anchor purely from 316L stainless it will have the corrosion resistance but not necessarily the tensile strength, measuring around 280 MPa depending on sheet thickness, a grade which means it is weaker than mild steel. If the anchor shank is constructed from 316L it will probably be way under-strength and not suitable for use.
This is why all stainless steel Rocna anchors have a high tensile shank, that delivers extremely high tensile strength and performs way better than any other galvanised anchor.
In addition all Rocna Stainless Steel Anchors are hand polished resulting in a mirror finish look that will last. This process takes many man hours and is thus expensive. The result however when on the bow of your boat is worth every penny!