I’m a noob, but often what drives up lens cost is the complexity associated with making the image better over the whole field of view. Lenses have various inherent errors (called aberrations) that are corrected by a combination of complex surface profiles on individual lens elements and stacking multiple individual lens elements to cancel each other’s errors out. A scope likely only needs good correction near the center, where the user will be looking most of the time, while a camera lens needs good correction everywhere so the whole photo looks good when you view it later. Wider field of view makes good correction much more complicated and expensive very fast.