Rain tree nursery sells rootstock (dwarf, semi-dwarf, etc) at around $3.50 ea. I've ordered from them and all their stock survived for me. They are going to take a few years to reach the size of tree you would get from someone like stark bros., but the price is right and if you want a smaller, earlier producing tree they will give you the final result you want.
I've found that my semi-dwarfs after a few years tend to give me sprouts from the roots, which I dig down carefully and cut off. Replanting them elsewhere give me a clone of the original rootstock. Once your trees reach a little size, your prunings in early spring can give you all the scion wood you want.
Scion wood is available several places
online. A few I see are,
http://waldenheightsnursery.com/store/scionwood-seed ,
http://www.maplevalleyorchards.com/Pages/ScionWood.aspx ,
http://www.masonvilleorchard.com/scionwood.htm They tend to run about $3.00 each, but a single stick of scion wood will often serve for 2 or 3 grafts. You can also get some scionwood from neighbors if they have a tree you like and they don't mind you cutting a few twigs.
I haven't used any of these sources for scion wood, but I've grafted before and it was really easy and all of mine survived. If it doesn't make it, that's $4-5 bucks on an experiment. Most of them will make it. You Tube it. Make sure you have good contact between the cambium layers and immobilize it and tape it with the wax tape to prevent drying out. The only real problem I can foresee is if you wait too late in the year. You want to graft them before they start budding out.
There is also T budding and chip budding, which I understand can be done later spring or summer, but I've never done that.
The one thing I would comment on is don't get rushed and dig a tiny hole and stick the tree in with mainly just dirt. It's way better long tern to dig a bigger hole and really give it something richer to start it out on. It'll grow much faster!