I'm really glad that Trigaea brought you so much joy, which was definitely the goal!
With Barnes and Noble, it's on their online store but it won't be on shelves, so you might need to order it at the counter. Let me know if you can't do that for some reason.
(I'm in Australia, so we don't really have B&N for me to check. B&N are getting it from IngramSpark, which is who I'm publishing through for non-Amazon channels.)