As you consider the various yard tasks and start to confirm in your mind exactly what lawn care services you may hire out, look at another angle. Do you need help year round? (Your local climate may determine this.)

Could you get by with seasonal help? Could you manage to do the weekly mowing, if you had someone take care of the occasional or more difficult chores?

It may be more difficult to find a lawn maintenance company that will accommodate a request for sporadic help. But at least verbalize what would be ideal for you. You may have to make concessions to get a particular company or a certain quote. 
Taking this approach will let you know what you can afford to sacrifice. It will also clarify for what items you are willing to pay.

(Side note: It amazes me how many people just decide one day to get someone to mow their grass. They randomly select someone working in the neighborhood or from the phone book. They only ask ‘how much’, he starts next week, and after awhile they start to wonder. “How did they end up paying so much for all the extras?” Or, “Why do they put up with the frustration of lousy work or unreliable appearances or worse?” Soon they are back doing the work themselves or trying a new company.)