Adi Shankar, who, in addition to the movies above, has also produced a number of bootleg fan films (including the recent Power/Rangers), explains how and why movies are funded outside of the studio system (and why getting a sequel to Dredd will be tough):

In a nutshell, he breaks it down with a simple equation: D + I + S, which stands for Domestic Value, International Value, and Subsidy/Government Rebate. Essentially, if the cost of the film is greater than the sum of this equation, than it's unlikely that anybody is going to put up the money for it, and if it's lesser than, there's at least a chance. This is the boring stuff when it comes to filmmaking, but it's also some of the most important, because movies require money to be made, especially at higher levels when you're dealing with bigger Hollywood actors. 

If you're wondering why there are so many bad movies out there, this is part of the reason. 

For more videos, check out Adi's YouTube page.

Source: Adi Shankar