Buying it is preferable if you can anonamously get a reasonable price but if that fails you could always just make it.
Materials:
Gallon of White Vinegar. (Try to get 9% acidity "pickling" vinegar)
Container of Lye
Sulfuric Drain Opener
pH paper
Distillation rig
Plastic bucket
Large cassarole pan(sp?) Pyrex glass and Corning ceremics are good.
Method:
Pour vinegar into the bucket. Add lye a little at a time. Bee careful about that volcano action. Also always keep lye bottle closed when not using it. And don't use a metal spoon.
Sodium Acetate is being formed. It is water soluable so you won't see it. Keep adding lye until it stops fizzing when more is added. Check the pH. You are shooting for a pH between 7 and 9. If it is below 7 then, when you go to concentrate it, some of the vinegar will vaporize and stink. The higher it is above 7 the more unreacted lye will be left over so add slowly.
Pour the liquid into your cassarole dish. The inevitable extra lye is why you've gotta use glass. Lye will react with the glass but very slowly. Whatever you do don't use an aluminum pot! Put it in the oven at 300C so that the water will all evaporate away. Expect it to take many many hours.
When all the water is gone you'll be left with a crusty substance that is mostly sodium acetate but also probably a little bit of lye. You will be happy if you are not using a white cassarole because it will be easier to see it and get it all out when you start scraping...
Slowly and Carefully add sulfuric drain opener. Distill and collect between 110-125.
Not quite pure but close enough for most uses...