I'm pretty sure that you must have lot's of oaks and maple trees around your area, those have lot's of leaves so many that a 21" wouldn't be sufficient to aim for a $50 per hour, you'll be overpricing people and next season you'll have no customers.
Around my area most people want a price before you do any job, sometimes you can get away with the hourly charge, I know I average about $70 per hour doing clean ups, that includes driving time also, but it hasn't always being like this, before I had stihl blowers an old 5hp lesco walk behind blower, tarps and rakes and I was making 25 per hour
now it takes less than half the time with this equipment redmax eb-7000 and 7001's fradan 12hp WB (thinking seriously about the little wonder), jrco leaf plow and a friend with a billy goat vacum (only 2 properties that don't have place for leaves).
I have this propertie that it's about 2.5 acres with around 50 large maple trees and oaks in the lawn area, pretty flat, it use to take about 15 man hours and was getting $375, now I charge $400 and it takes 6 to 6.5 hours.