Hi,
if you want to plant plants, then go for a grafted cultivar so you can expect something within a couple of years.
Also there are really fancy cultivars, but they can easily cost 100$.
I would not buy seedlings for the simple reason that a tree gets a different hold to the ground when it germinates in it.
This may not be crucial for an apple tree, but walnuts easily get more than a houndred years old and will become the largest
tree in your orchard(plant it in the north), so that one year you save by taking a germinated seedling
does not justify the drawback the adult tree may have, at least in my opinion.
There is a reason why the seedlings are so cheap
EDIT: It takes 10-20 years for the seedling to fruit, and significant yield can be expected in the fourth decade of its life onwards.