The advice was: open a walk-by pizza restaurant in New York. The book went into a bit of detail on all the advantages this particular business entailed but skimped quite a bit on the downsides.
Despite all the upbeat advice here you should be realistic, you will have to sell yourself pretty hard to achieve more than the going rate in your neck of woods.
Personal experience, I worked on a 10k USD data mining project in a Eastern European country last year so 10k is doable even there. However, my take was 1k for maybe 2 months of weekend work. The hustler/rainmaker got most of the money, while some money went to a PhD brought in for prestige. While I could complain that I did 90% of the programming/dredging/analysis involved, I was under no illusion that I could procure the job myself. The amount of BS that was involved in procuring the job was beyond my tolerance level. Now some people can do both: handle corporate BS and do programming but I doubt it is true for most of us.
TL:DR It takes more hustle than programming skill to get those $100/h gigs.
Advice: If you want to be realistic, try to go 50/50 with a hustler, you are unlikely to get to $100 an hour within 4 months by yourself.