Costco does not really has a garden center. In the spring, they bring in flowering and fruit trees for a few weeks. That’s it. In my area, April is the time to look for fruit trees. They offer different varieties from year to year.
I bought a nectarine, Freckled Face last year. This year, it offers September Free nectarine. Their trees are Burchell’s which sells fruit trees to retail customers at a ridiculously high price.