Hi K8memphis,
The strength of vanilla extract in the USA is regulated by the FDA. If you are wishing to make your vanilla extract comparable in strength to that which you can purchase at a store then the ration is as follows: 13.45 ounces of vanilla beans extracted into one gallon of water and 35% alcohol. This will produce what is called "single fold" or "1x strength" vanilla extract. To make double fold (2x) you simply keep the the water/alcohol mixture the same and double the vanilla beans to 26.7 ounces. Of course you may not wish to make a gallon at a time so you just reduce all in proportion. So if you would like to make a quart then you use 1/4 of the vanilla beans specified above. Vodka really makes the best medium for this. It is already at 35% alcohol and comes in reasonable sizes. I see that someone else posted 40% alcohol is what they use. There is nothing wrong with this. The extracts in Canada and Australia seem to be at about this percentage of alcohol. Make sure you chop up the vanilla beans before you put them in the bottle.
Of course it is less expensive to just buy vanilla extract but when you make your own you can experiment with vanilla bean pods from different regions to make different taste profiles. For example, you mention Nielsen Massey's products (a friendly competitor of ours). They have excellent product but it will have a very different taste profile from our vanilla or another company's offerings. Many chef's that we work with keep a stock of vanilla from a couple different suppliers. Although people use the word "vanilla" to mean plain or simple it is actually an extraordinary flavor with amazing complexity and is a joy to experiment with. Enjoy!
