I'm not sure the rising cost of new machines is due entirely to the larger harps. We all want our new machines to do back flips and come with lots of bells and whistles as well as long necks.
I live in an area where industrial machines are a fairly common thing to see for sale. They all have long necks. They are also more specific. Straight stitch, or just a straight stitch and a zigzag, etc. They aren't as expensive as the new quilting/sewing machines I've seen.
The newer domestic sewing/quilting machines all seem to have hundreds of decorative stitches, embroidery & font capabilities, mirror image & button hole selections. Lots of fun stuff.
It wouldn't surprise me if the new machines come with 'smart' options.
Imagine.....program your machine to turn itself on, thread itself, adjust the tension and maybe even make the coffee... from your smart phone. All ready for you to sit down and enjoy as soon as you get home from work, or as soon as breakfast is finished.....
