I think it has been well pointed out how "different" everyone's situation might be when beginning to "fulltime". Even fulltiming is different to some folks. Obviously there is not a one size fits all budget. It's similar to buying a house, everyone has a different situation going into buying a home, starting a family etc. Each individual has to take the time to assess their situation, what assets they have and how to procure and maintain their "dream". It's never simple, nor is it easy for most. We were no exception to that and in fact, spent a great deal of time scrubbing our own financial situation to see if it was possible and even then have found that our situation at the moment will change dramatically in 9 months when we no longer have a tuition bill to pay for our son. Still being wet behind the ears ourselves in our jouney, we have discovered this and tell people this when they ask. 1. Be honest about your situation 2. Be prepared to continue to make sacrifices as you did living sticks n bricks with a 9-5 JOB. 3. The sky is the limit if you are willing and able to work a little to make things easier (just as most do prior to fulltiming).
We are retired military, so we have a little income from that, but we knew we would have to workamp until our son graduated in 2013 to pay for his schooling and that is what we are doing. If we did not have that income from retirement, we likely would have changed our ideas on our ability to fulltime when we decided to. However, we knew what we must make in order to continue to make things comfortable. We didn't have a house to sell when we started, but we did have a nest egg that would have been used when we "retired" at 60ish, but instead used it now so that we could retire at 40ish. That helped to pay off the bills and put a chunk of change down on the new camper and truck. We were quite concerned about work this upcoming winter, but that too has worked itself out and instead of being where we wanted to be, we took a job in a less ideal location but the pay was right. All that being said, again, we KNOW that next year when we no longer have to pay for school, we won't have to be as particular about the types of jobs that we take to continue to be comfortable and in fact will likely only have to work one season vice two.
It is such an individual decision and situation that I don't think there is a book/resource out there that will give everyone all the information that they are looking for. No one else can do it for you.