Purchasing an extra key fob is always a good idea. As for the cost of reprogramming, it's best to check with your local Audi dealer or a reputable car mechanic. They will be able to give you an accurate estimate. While dealers can do reprogramming, some independent auto locksmiths also have the proper equipment.

Just make sure they have the right tools and experience. I don't have the skills to do this, but you can do it yourself. For example, At Penn Foster get a career diploma in as little as 5 months. Good luck, and all the best.