This subject sometimes stirs up a hornets nest! Prices are regional, as well as based on what size jobs you're looking at. 1 to 5 acre jobs scattered about where you'll do as much trucking as mowing usually warrant a higher "per hour" or "per job" rate as opposed to bigger acreage.
I own a mowing business where we do larger acreage primarily. (Property maintenance for a legal conservator) The bulk of my work is 25 to 100 acre properties. Some even bigger. I'm in rural central Kentucky. As a rule of thumb, the going rates around here are roughly $1.50 per horsepower. (ie 40 hp tractor w/ suitable mower, $60 an hour. 100hp tractor w/ suitable mower=$150 an hour) Fuel cost and cost of living in general are starting to drive that up slightly, but the volume of "competition" keep raises in check right now. Bottom line, if you want to stay busy in an area with plenty of competition, you have to find a way to make money at competitive rates that mirror the competition's rates.
In some urban areas, primarily east coast and west cost, rates are more than double.
As far as added lines of work such as spraying, there again, it depends on available work and local competition as to that being a viable option.
In just one year, I went from start up business to 4 tractors, a total of 6 employees, and all the work we could handle, even in a severe drought condition most of the summer. Keep in mind, 75% of my business is from one client and that was pre-arrainged before the years started. Without that one key customer, the business would have struggled to stya busy with just myself and my 2 initial employees.
I would think your location should be very simular to mine.