I see you were focusing on newbies. It is often a shock when people add up the necessities of a Disney vacation, or their view of necessities. When we first bought DVC in 1996, we got a 3 BR Grand Villa and treated family a few times. Even though we provided rooms and I cooked several big meals, one family in particular was not prepared financially, even though they had been several times before. We found out during the trip they were maxed out on credit cards and bought a 60K SUV right before the trip which made it quite uncomfortable for us as hosts. They complained about not having any money... That was the last time we invited anyone other than our son and DIL (they have brought friends but they get their own villa). We sometimes hear "do you still own that Disney thing" but ignore it?
People are shocked when they hear it is at least 10K for a week for four people (transportation included) and that is a REALLY tight budget. 15K-20K a week adding in ADR's and an upgraded villa...is really easy to reach.
Personally, I think a family that has a "planner" can figure out a good budget, however trips with multiple families can be a disaster. I have helped dozens of friends plan family and multi family trips and everyone came back happy because they were prepared. I'd say the best thing a newbie can do is either find a friend who enjoys Disney planning or going through a
travel agent who specializes in Disney so the financial pain is exposed early on!