The whole reason why 3D NAND happened and higher layer counts enable cheaper, higher density storage is that it doesn't require an etch step per layer to build the memory cells. It's just deposit several dozen layers then etch holes down through all of those layers in one step, followed by filling in those holes with different materials. (Though at 276 layers, it's a stack of more than one deck of layers built as separate batches. The aspect ratio of the holes is the limiting factor.)

But aside from that, the cost of the NAND is the variable portion of the drive's cost, not part of the fixed floor of cost necessary for a drive of any capacity.