I was reviewing a cookbook this week on microwave cooking. In the cookbook was a recipe called Chai for One. I googled it to see if I could find it online. I did, or at least one very similar.
Here's the recipe link: http://splendidtable.publicradio.org/recipes/drink_chai.html
The spices in the recipe in the cookbook were halved. So, I would start with them halved and then try them doubled and see which you like better. The cookbook also used evaporated milk instead of sweetened condensed. I think that's why the spices were doubled in the recipe online. I have a cup in front of me (made with have the spices and evaporated milk) and I added 3 Tbsp of the mix to a cup of tea plus two spoonfuls of sugar since I like it sweet. Keep the mix in a jar and it should keep for up to a month according to the cookbook I read. I think next time I'm going to try the recipe I linked to online with the sweetened condensed milk.
I'm so glad to find a good recipe to make chai from scratch! I like decaf chai and it's been hard to find a good decaf mix. The powdered mixes have extra stuff in them and are usually caffeinated. I think it will also end up saving me a lot of money =)