TBH, I don't think that a Disney vacation is affordable to families that are on tight budgets to begin with. It's expensive to get there (especially if you're coming from Europe) and once here, the cost of tickets, accommodations and dining can be dizzying!
The way that I fund my Disney trips is probably not going to work for you. Everyone's situation is different and what works for one person may not be doable for another.
For example, there was a deal posted today where if you purchase a $150
Best Buy eGC, you got a $15 eGC bonus at a later date. I bought $300 worth of eGCs and I'm contemplating purchasing another $150 to max out the deal. Why Best Buy GCs? Because I can use them to purchase Disney GCs in the store. I can do this because I have the cash available to be able to cover a $450 expense and not think about how I'll pay the electric bill as well. I can't imagine someone who is on a tight budget being able to do this without making huge sacrifices in their daily lives.
I do credit card points and rewards programs to fund most of my Disney fix. It's more of a game (or challenge) to me to see how much of my vacation can be paid for without dipping into our designated vacation savings account. All of our monthly expenses get paid with a rewards credit card. We also own a small business and pay most of our overhead costs with a rewards credit card. We accrue a significant number of points this way. In order to make this worthwhile, every credit card bill gets paid in full each money.
I get anywhere from $75-$100 in cash and GCs each week from online rewards programs that I run while working from home. Some weeks are better than others. Some programs are more consistent than others.
We made our first DVC purchase with cash a few years ago when the real estate market crashed and we made our most recent purchase (again, with cash) this past year before DVC resale prices began to skyrocket. When we have more points available than we think we will use, we rent them out to cover the cost of our annual dues and then some. I use the cash from the rentals to purchase Disney GCs at a discount (like the aforementioned Best Buy deal) and then pay my dues with the GCs.
We buy annual passes. DVC members get a discount and I pay for the APs with Disney GCs that I either got for free using rewards programs or at a discount whenever there's a deal available. We get two or more visits out of an AP and then we (usually) take a year off. It ends up costing less than if we purchased MYW tickets for each visit.
So, quite often when we tally up what we spent on a week-long Disney trip for 2, it comes down to a very small amount of cash from our regular income. 9/11 fees for the airline tickets, which we get for free on points, and a small amount of cash for tipping skycaps, DME drivers, Mousekeeping and bell services are all that we actually pay OOP for. Pretty much everything else is covered with rewards, discounts and our DVC points.