A friend of mine was looking to buy a tree for her house, and came across this:
www.arborday.org/
It's a good source to both learn about and order trees you may want to plant around your house. If you're a home owner, or you live with home owners, this is an excellent way to get good stuff for the house (Potted or bare-root).
And they're cheap, too. If you sign up for membership for $10, they send you free trees! Specialty / specific trees run about $10 each, it looks like, and $5 shipping.