Is it easy to make my own Vanilla Sugar? Some background: We had some visitors from Austria recently and they wanted to make a cake. 

The cake called for a couple of ingredients not terribly easily obtainable locally and which I am not too familiar with. Quark and vanilla sugar. We understand from our friends these are pretty much staples in Austria. But we had to track them down.

We are experimenting with the left-over vanilla sugar in fruit crumbles and various other recipes where sugar is required. 

Turns out vanilla sugar has a pleasant delicate sugary vanilla taste. But the product just seems to be caster sugar with a vanilla pod inserted.

When we run out can we carry on "making" more by just sticking a vanilla pod in 500g of sugar. Does it require a certain amount of time for the vanilla to infuse into the sugar? Is there anything more to it than that, or is it that simple?

P.S. The cake was called Topfengugelhupf, in case anyone is interested.
The best advice I can give is to use Alton Brown's recipe to get your timeline.  

Vanilla sugar is very easy to make, and I hesitate to answer with a link, but my advice would be the same thing as he wrote, because this is what I was taught.  

Basically, you want to cut the pod in half, and scrape the beans from the seed into an airtight container.  Then drop the scraped pods in the container, give it a shake, and let it sit for at least a week.  AB recommends 1-2 weeks; I tend to just let it go indefinitely until I need it.

A lot of people don't scrape the pod but I find that it adds a lot more flavor if you do it that way.