You can use cheap vodka for this.
After getting the beans in a jar, secure with a light fitting lid. Shake vigorously once a day for the 1st 2 weeks. Then once a week. Keep in a cool, dark place or room temp. okay. Best to wait 6 to 12 months to use it. Keep it going with vodka additions until seems weak. Then add a bean or two. This way you will not run out of vanilla.