I don't know that I'd sell the entire domino unit, but you can buy the fence as a separate item. Selling the whole unit and re-buying would probably be cheaper, though, unless you can find someone who wants to trade fences with you.
There are some who strongly prefer the pinned fence over the flappy fence, so there's a market out there. Some use the pins as a locating guide, others use them to trap the material and mortise on an angle.
I posted a "WTB (want to buy)" in the Classifieds a while back and found a flappy fence for sale that I put in the systainer with my pinned fence model so that I have both options as the need arises.