This is inexpensive and you can make it to your liking! I used just regular Lipton tea bags. I have used green tea in the past, but that is a much lighter taste. It's fall, so mulling spices are easy to find - usually lying around the apple cider in the fruit section. At least it is up here :-) I originally used blue agave syrup to sweeten, but sugar or maple syrup will work as well.
Pour two cups of water into a small pot. Add tea bags and spices. I also added a little peppercorn for spice. Bring to boil.
Let boil for about a minute. Set on simmer for about 15 minutes. Tea should be a dark brown. Taste to see if the spices are strong enough. If not simmer a little more.
Once you are happy with the strength, turn off stove, remove tea bags, and pour mixture into a large cup or small pitcher through a strainer of sorts.
Now you can add sugar, or whatever sweetener you choose, to the tea. Or you can sweeten each individual cup. Although you don't want a super sugary chai, the sweet does bring out the spiciness, so don't be stingy with the sugar.
Fill a smaller coffee cup with the tea a little more than halfway. Add milk until the mixture is a medium brown (or lighter if you like). Heat in the microwave for about 50 seconds. Enjoy and keep away from cats :-P