Disney is insane. My wife is pushing to go first week of Sept and to stay INSIDE the park. Would rather stay at a nicer hotel outside the park with points.
Anyhow, I went several years ago with my oldest. At that time, we went for 4-5 days, it cost about $3-4k. Now, I made pretty decent money back then, not great, but good enough. I was fascinated by people watching and I KNOW there were families who weren't nearly at my income level spent countless dollars on garbage ****. I can't even imagine how hard a Disney trip is for low-middle income folks.
And on top of the costs, the wait times are insane. I hate the place. lol
Couple of things (having lived in Orlando for most of my life)...
First, don't rule out staying at a Disney hotel, but go for a cheap one. You get free parking in the PARK lots (not just your hotel) and you get the "Magic Hours" (early admission) on various parks. The extra hour ALONE can get you on one of the "longer-wait" lines before the park really kicks into high gear.
Also, take advantage of your times, figure out how to hit some of the "longer-wait" rides during big events, like the parades and whatnot. And don't be afraid to wait until the last minute, as long as you are in line when they are closing the park, they'll still let you ride.
Eat at odd times, don't stand in those lines. Don't be afraid to walk away from a long line. I usually do mid-afternoon lunch and a later dinner to minimize the waits.
And use the fast-pass as best you can. I think you can even schedule that stuff online, you don't have to be right there in front of the ride. And mix in some of the other stuff to take breaks, like the Tiki Bird show. Sit inside in the A/C at the times when the "E-ticket rides" have the longest lines.
I was at Magic Kingdom 18 months ago while I was at a continuing education conference (staying at Grand Floridian). The park was packed. They gave us an "after 5 pm" ticket. I jumped on the monorail and hit Big Thunder (5 minutes before closing), Country Bear Jamboree, Hall of Presidents, Haunted Mansion, Jungle Cruise (during the fireworks), Peter Pan, Pirates, Splash Mountain (last time ever for the Song of the South theme), Seven Dwarves Mine Train, and Tiki Birds in a matter of six hours, plus I got some tacos at Pecos Bill's and a Dole Whip. Only thing I missed out on was Space Mountain.