Well, not experienced in that sort of thing, but I can tell you the local tree farm here supports itself selling Christmas trees. They have probably about 50 acres on an upward slope. Trees sell for $30-80 cut pick ur own, but they have to give up much of the holiday season for sales.

As far as buying trees, seedling can be had for very cheap though your extention office or the arbor day society, or like offices.

I would think that selling tree starts to full size wholesale nurseries would be the more profitable way to go and would require less start up $$ than growing trees to full size. It would take a lot of land to grow full sized trees, not to mention the equipment for digging and moving etc.

google wholesale trees ... I buy bare-root trees almost every spring from a local nursery who gets them shipped bare-root from Canada. This is a great niche for them.

They sell trees that are suited for our area, and as many unusual or not so common trees as they can find.

Figure out what you want your niche to be ...

Join your local/state nursery association. You may be able to network with others in your area that can put you on the right track. There are a lot of expensive mistakes that you could make. Don't jump into it without researching it thoroughly, and good luck.