The OP is asking for tips and strategies for big cost savings that will lead toward an inexpensive trip. Tips like purchasing tickets without the park hopper option, or having just one drink instead of two with your dinner, are great... but while they'll save a few bucks, they definitely don't lead toward big cost savings let alone an inexpensive trip.
Driving to WDW may not seem sexy, but in the past, the average savings for a family of four was nearly $2,000 (flight+rental car vs. driving). Modern entertainment (including cellular data) makes the trip more bearable for kids than ever before, but there's plenty of ways to keep kids engaged, such as stopping at points of interest to the family. But the good news is... if you begin planning your trip early, you're sure to find a low-cost flight (with a few exceptions) ... even on Saturdays during July. Frontier Airlines is currently selling flights into Orlando from around the entire country for $100-$200 per round-trip (a round-trip is required for the lowest fare; additionally, a bag will add $60-$70 to the fare, but I would encourage anybody to minimize the amount of baggage they bring; buying the stuff you didn't bring can save you a lot of money). Many airlines have matched, including from secondary markets not served by Frontier. Southwest, for example, is selling flights from Indianapolis for $79 each way, and has recently been selling markets like Chicago, Baltimore and Pittsburgh for less than $100 each way (keep checking, fares fluctuate). It's a good time to be traveling -- throughout much of the 2010s, it wasn't uncommon for a "cheap" airfare on a Saturday during July to be $400 or more round-trip.
Note that you should research airfares from airports within several hours driving distance... a five-hour drive to Indianapolis, for example, could save you hundreds of dollars (just remember you need to return to that airport if you drive... and factor the cost of parking and gas into your comparison). Also note that most of the cheapest flights generally have subpar times... some of Frontier's flights in the East depart as late as 10:30PM and get into Orlando as late as 2AM, for example.
And yes, staying off-site will save you a lot of money. In the summer, one week at the All-Star Resort is going for about $1,000 (prices I'm listing include taxes and fees). The Comfort Inn Maingate is going for about $500, which includes a decent breakfast. The Maingate Lakeside Resort is only $250. I've stayed at the Maingate Lakeside many times through the years (under the LaQuinta, Best Western, etc. banners, also as an independent). "Back in the day," when you bid for Priceline hotels and bonus cash was frequent, this place was basically free. At $250/week during July in 2020... it's still a steal. You get a lot for your money -- rooms are dated -- they resemble that of a Moderate Resort during the 1990s, with a flat screen -- but generally clean. You get daily housekeeping service, toiletries, in-room coffee, fridge, WiFi, and a safe. Parking is free, and there's a free shuttle to Universal/SeaWorld and the Transportation & Ticket Center (generally 1-2 departures to the former, 2-3 to the latter, depending on the season; they sometimes do other parks like Epcot seasonally). The hotel grounds are beautiful and include a nicely landscaped pool and kids area. The last time I was here, there was an old school arcade and a building that showed kids' cartoons and movies. There was also a restaurant that served a fairly cheap breakfast and dinner buffet, as well as a snack bar and Pizza Hut. Poolside drinks were on the low side, too. They use to give every guest one free breakfast and a couple free drinks, but I don't think they do that anymore.
But if you drove and stayed at the Maingate Lakeside Resort, you'd be spending around $500. You don't have to spend a lot of money, to have a great family vacation.