I would think this pricing is more based on a commercial positioning decision than actual economics - the manual is cheapest, and it maybe has less options for

I would think this pricing is more based on a commercial positioning decision than actual economics - the manual is cheapest, and it maybe has less options for other fancy accessories, so that there is a very cheap "prices begin at" option which few people actually want. The margins may be even smaller there because of the extra cost of specific models, but it makes sense to have these available because then the volume models can have a slightly higher sales price.