Are you mad?
Know this, you will not save one thin dime by making your own doll, you will only loose at least the amount of money you would spend on a "cheap" doll and hopefully gain some valuable experience. The first of which is be familiar with drawing the human form, and modeling clay. Making practice parts out of modeling clay is very helpful. So are these blog posts. Feel free to ask questions! I've worked with all of this stuff at one time or another.
http://dolfielittles.typepad.com/blog/2 ... stuff.html
http://dolfielittles.typepad.com/blog/2 ... cases.html
http://dolfielittles.typepad.com/blog/2 ... g-kit.html
http://dolfielittles.typepad.com/blog/2 ... sting.html