Flying Business Class for cheap isn't as hard as people might think. Many airlines don't manage to fill all their business class spaces. That is why they sell business class seats to another company (publisher) for cheap. This publishers (most of the time) has built an audience to spread the word.
Everybody wins: The Airline will sell most of their seats, the publisher is buying it for less but selling it to their audience with a small margin and the consumer/passenger won't pay the full price for the seats.
A Business Class is often a class custom-tailored for business travelers. The passenger should be able to work and relax. The goal is to make the flight as comfortable as possible for the business traveler.
Get an upgrade. Sounds simple right? It isn't that easy tho.
Upgrade Professionals say that timing is one of the most critical aspects when talking about upgrading to business class.
The strategy: Waiting as long as possible to book your flight. Sometimes the airline is fully scheduled for the economy but can't sell all their business class seats for the flight (like mentioned above). They will try to sell some of their business class seats to people who aimed to pay economy. You have to do a little upgrade. And there you go, you are flying business class. However, if you are unlucky, you will only get some bad economy seats.
Another idea: Dress like a wealthy person. I am not speaking about looking like the next prom queen/king — just a casual busy looking person.