You can get leaflets delivered, but in my experience it has been the riskiest investment that i have made, and i am running at a loss so far.
I have used six different companies or people the best return was when i delivered them myself and when a very good friend of mine did his own leaflets alongside my own.
All the others bar none have given a poor return and i can only conclude this practice is endemic in that industry, you may find a young person who wants to earn some money, or a guy who's out of work and wants to earn a bit of cash, but my theory is they start off with good intentions, then the penny drops.
Call me cynical if you like but throwing money away does that to you, if you have someone and you can show a reasonable return then great, my advice would be don't invest too much at any one time and monitor closely.