My view of instructables contests.
The majority of the winners for contests can already afford the prize to the contest.
Really- The winner for the shopbot challenge is a voice controlled storage container? Great! Except to make the project it only costs about $3000 dollars. Which most people do not have to spend on one project. Same for most projects- the winner is usually a person who builds this huge, elaborate project which can cost thousands of dollars and requires an insane amount of special tools (really, does everyone think we all have $50,000 laser cutters, a CNC, AND a 3d printer???). Would it be that hard to run a contest where the total amount spent cannot exceed, say $100, excluding tools? This would cover most of the user base, and allow people with not much experience or money to enter a contest with a shot at winning.