I’m assuming you want a large quantity of trees http://www.willamettenurseries.com/fruit_tree_seedlings. I would not pay much over $1 each. Think about how your going to avoid diseases which typically means dealing with a single great source or two. I can’t help with the fruits of those because I’ve not personally grown them but they say they are ok for wildlife and even pie. Think $100 or so would get you well on your way to a large wild tree orchard. Graft them if you feel like it later. I think Malus antonovka is a great choice of rootstock and I have some myself.