If you are interested in fruit tree bartering and homesteading...plant a lot of American Persimmon, paw paw, and some variety of crab apple that is good rootstock. Possibly from seed. With luck they will multiply. Learn to graft improved cultivars on seedling rootsock.

Depends on the type of tree, but many fruit trees can't just be grown from seed. Trees like apples, pears, cherries, etc are almost always grafted cultivars. Seedling trees most often do not produce superior fruit, so grafting is used to produce usable plants. Even the rootstock itself is very often a specially selected cultivar. Just as with the scion, a cultivar rootstock is used to provide desirable traits.

There are multiple commercial sources for fruit tree rootstock and scions (especially for commonly commercially grown types for fruit), but a good source for the hobbyist is the North American Scion Exchange. They have a Yahoo group, a website, and a Facebook page. In actuality, more activity seems to be concentrated around their Facebook page.

You might also want to look into obtaining grafted liners and growing them, if you are really considering doing it on a large scale. Many mail-order sites sell smaller, grafted fruit trees.

Here is a link to many fruit tree sources. You will have to review them to figure out which would be of use to your project. The information on the link will give you a general idea of what they sell, contact information, and a rating based on the Garden Watchdog site. Sources for Fruit Trees and Plants