Question has too many variables to answer completely.
I have a minimum of $30. My overall average is $35. The average subdivision lawn is $35-$40. If the person has a lot of trees or flowerbeds all over the lawn then I go up to add for the extra time involved. You need to find someone respectable in your area to help you get a general idea. Don't find the lowballers to help you or you will become one. (we might reconsider your membership )
You will find people that will pay for quality. Don't undercharge just to get work. Big mistake.
The question is related to how much time is needed to do the job and how much you want to charge per hour. An empty acre lot will take x amount of minutes to cut. An acre with a house, pool, driveway,swingset, will take less time to cut, but a lot more trimming is involed.
When i am Figuring out how much i should charge i dont really think about the things that everybody has been talking about.(not being disrespectful) The things that i look at are the cost that my competitors are charging, because it doesnt really matter what you think the lawn is worth, it is what the customer is willing to pay you for it. However, if the price they are willing to pay will not pay for your costs and time, find another. There are more out there.
Know your market, but ask what you want based on the other criteria. If you don't get the job, so be it. There is more out there, and your better off with better paying customers. I'm generally higher than the person before me. I hear all the time, well I only paid $$$ last year. If they were happy with last years service, they wouldn't be calling me. Most people that have had several different people cutting over the years are willing to pay a premium because they know its hard to get someone to show up all the time, and be there once the summer heat shows up.
You can't be interested in quantity, quality is what makes the world go round and new business show up at the door.