It is a good idea for a service, if possible please consider something like https://www.mobileworks.com/ as vincvinc mentioned below that tries to be socially responsible for crowd sourcing instead of mturk.
That said, I've actually used mechanical turk to earn money in some of my low points (was living in my car working on a startup, out of cash, crazy/long story). I didn't make US minimum wage, but if I were living in Bangladesh, for example, it would have been OK money.