Another thing I feel is odd is the charging for technical support on the code samples. Either the code doesn't work, in which case that's a bug in the _book_ and should be fixed without paying for that, or it's a failure on the reader to set up the right environment, in which case the issue is likely to be minor and could probably be answered on Stack Overflow.
If it was support implementing the ideas in real world projects that would be worth a lot of money, but that doesn't appear to be what they are selling.
I think it fair to charge for technical support. Of course you could turn to Stack Overflow, but some people can and will pay someone else for assistance.
Another thing I feel is odd is the charging for technical support on the code samples. Either the code doesn't work, in which case that's a bug in the _book_ and should be fixed without paying for that, or it's a failure on the reader to set up the right environment, in which case the issue is likely to be minor and could probably be answered on Stack Overflow.
If it was support implementing the ideas in real world projects that would be worth a lot of money, but that doesn't appear to be what they are selling.