The general line back to 'pocket money' part timers, an people who only charge a 'small amount just to help towards gear' is that there's no such thing in the eyes of HMRC, where as soon as you have started touting for work - you're running a business.
We've been through it all lots of times, but people charging really low rates aren't even necessarily part time, for instance, because of what it costs me in time to set up and take down a studio, I couldn't get anywhere near your pricing - and you're making money with large overheads

Trying to compete with you would see me working for less than minimum wage by factors.
The market has always been diverse, there have always been part timers and full timers, as others have said - market forces ensure a status quo, the state of the economy generally has much more effect on business. Average prices were climbing considerably before the recession and at best have stagnated for a few years (not scientific, a gut reaction) and there's also regional variations in spending based on the economy rather than the number of 'part-time' photographers.