trading something you can't use for something you can is usually a good deal. Even if the shuttle turned out to be "worth" more than the needles, you'd need to go to the trouble of offering it for sale, and sometimes that does not work out as well as we'd like.
I've seen the needles sell for as much as $3 each - and a lot cheaper in larger lots.
You may want to stop referring to your machines as a "New Domestic" as by today's reckoning, it's the older style Domestic. the "new" style is either going to match Singer or White - and you can't use either of the needles or shuttles that work with the "new" style Domestic - you need the original style.
So please, make sure you are getting the correct needles. The do not have a wide shank (they are the same all the way up) and they have a funny notch in the top end.
I don't know enough about shuttles to have a clue what yours is for, and until you can determine that, value would be low.