We actually have done it before - loved it! I did it as a Christmas present for Otto and we used it in spring 2009. I just told him we were doing it instead of buying a gift certificate because the price varies by what kind of beer you make, what supplies you need, etc.
It's kinda pricey but he loved the experience, hence we're doing it again. They have a big menu of the beers they can make - you pick from these and they give you a recipe to follow. For ours, we liked one type of beer but wanted it to be a little less bitter and a tiny bit sweeter, so they adjusted the recipe according to what we wanted.
Here's the process: http://www.shenandoahbrewing.com/brewing/guide.html
Here's the pricing: http://www.shenandoahbrewing.com/brewing/prices.html
If you're bored Saturday between 12:15 and about 3:15, stop on by and have a beer with us while we brew!