A.M.
I am a mom with 4 kids and a real estate license. It will depend on the agency you work for and how you run your business. I would suggest before you actually get licensed that you shadow some one like me who has kids and does RE to see what it is really like and you can get an idea of where you would invest your money.
I love my work and it gives me flexibility that is incredible. With that said, it is also a very challenging job and not exactly low in overhead. I would be glad to discuss further with you or even meet a few times, it is not just as uncomplicated as what will I spend. What I have spent has been very different each year I have been a realtor. I will say I have learned alot and would be glad to share more.
I would suggest the book the Millionaire Real Estate Agent. It has a section on budgets that would give you a good idea where your money would go. I would also suggest that if you are a mom that you join a team, with out team work I would never be able to give both my family and my clients what they need.