The time that you take for completing the setup of lawn would be really huge. You would rather feel that you could have invested your time in some other activity that would give you good returns. Probably completing a course might add more value for your career and could get you more increment in job. You could otherwise even spend time in looking for a new job. How about doing painting by self than outsourcing to a crew so that you could save money that is paid to the crew. Like this there is direct savings and the indirect savings that are not evaluated by you as opportunity savings.
Of course, even the expenses made by you for fencing the lawn with the small logs around it, so that kids do not enter into it, should also be considered if you have to think about the intangible return of enjoying the fresh air from the lawn. You could rather pay the entry fee to a park and enjoy jogging in the park to get fresh air. However, owning a lawn in the independent house would be a value add to the house as it would enhance the beauty of the premises. So, make sure that you get the best herbicide for lawns so that you do not have to worry about the harm if any that is caused to the small children that are likely to move around the lawn.
Also, the pets that you grow would also go near the lawn and hence they should not be impacted with the regular weed killers that you use to kill the weeds. Since the herbicides would not harm the plants that are in the surrounding of the weeds. On top of everything else you could stay with peace of mind as you would no more see the weeds that are spoiling the landscape of your lawn.