I have to do some reading....but do you just buy plain vanilla and put some vanilla bean in it?
I've read the the grade B beans actually work better for extract (but it's been so long ago that I can't remember WHY, just that it DOES)Step-by-step photos and instructions for how to make the best Homemade Vanilla Extract! All you need is vodka, vanilla beans and a few tips and tricks. You'll find that homemade vanilla is less expensive (store-bought vanilla extract can cost $4 an ounce) and more flavorful than store-bought...tastesbetterfromscratch.com
Vanilla beans are less online because you can get grade B. The beans I bought came with instructions too.