John, you might try to stock all the trees that the
Georgia Forestry Commission carries, except have them available all year and with no minimum order. GFC is geared to high volume orders for winter planting, which is one method of marketing, but that leaves plenty of niches for other people to pursue.
There is also that nursery in Tift county that does a good mail order business. You could compete against them by
actually knowing what varieties of trees you are selling.