Does your State offer nursery stock? This is the cheapest option in NY that I've found.

If you're in it for the long haul, and want to plant alot of trees, you might look into hardwood cuttings as an option, I'm considering it right now for Apples and Grape vines.

http://www.freeplants.com/hardofdecid.htm

http://hcs.osu.edu/mgonline/PLANT%20...02/05ase02.htm

http://www.ces.ncsu.edu/depts/hort/hil/hil-8702.html