$0....I installed BeerSmith2 yesterday
Even though I'm not even AG brewing
yet, I've thoroughly enjoyed using it. You can make it as simple or as complicated to use as you want.
For someone like me that has never really designed a beer, the 'Style Guide Comparison' is particularly good.
The only problem, which I'm not really sure if it is a problem, is that the hops and grain in the program often have differing AA% and EBC. You can easily add your own and/or change them. The longer you use it and create your own profiles, the more personalised and easy to use it would become.
The tutorial vids that Oliver posted a link to are quite helpful too.
I look forward to getting a lot of use out of this program..........eventually.