It seems that even keys can’t be simple (or inexpensive) anymore…sigh…And it seems as if each manufacturer has their own key design, so the ways you can replace are limited. I can’t say whether the dealer is BSing you; it could be that they choose not to have key cutting equipment and expertise right at the dealership. Although I would like them to be a little more transparent about how they do it.
Try calling a local locksmith and get another opinion. I got a replacement key for my Toyota - in that case, the dealer was cheaper than my locksmith. I’m in the process of getting a replacement key for my Honda - in this case, the locksmith was cheaper than the dealer, although the locksmith supplier isn’t particularly reliable; it’s been 3 weeks since he ordered it.
My Toyota key was about $250. The Honda one will be around $110-$120.