It's 99.9% of every kids' dream to visit Disney World/Land at some point in their life.
I was fortunate enough to be able to take my kids back in 2008 for almost an entire week. Lydia was only 6 months old and Alanna had just turned 5. Granted they were a tad bit young to enjoy most of what Disney World had to offer, but it was ok with them. Lydia, for the most part, was content to sleep in her Jeep carrier with her little head on my chest. And Alanna was happy visiting all of the princesses and Disney characters that she could. Missing out on the rides didn't phase her. Heck, she preferred not to go anywhere near them.
Now, I understand that Disney might not be financially logical for a lot of families right now. And that's fine. Your children will not curl up and die for not being able to walk down Main St in the Magical Kingdom.
What you CAN do... and what I'm currently doing right now... is plan a trip for a few years in the future. I've told my oldest that we will attempt a journey back by the time she's 10 years old (she's 7 now). That puts my youngest at 5 (the age Alanna was last time, and honestly, I suggest waiting until your youngest is of the age where they are self propelled and compeltely mobile on their own... it's a pain to try and juggle infant, a diaper bag, and a stroller using only 2 hands onto one of the shuttles between the parks). I have given Alanna the task of making her very own Disney Piggy Bank. Using construction paper, puffballs, stickers, glue... any crafting objects she desires.
She's happily agreed to the task and looks forward to putting every bit of spare change she can procure into her bank. Forget that the trip is still 3 years away... as long as she knows she's working towards it she's good to go. And she's excited that she's going to be able to spend her own money on pretty much whatever she wants. When Lydia is a tad bit older we'll start her Disney piggy bank as well. I want her to be as involved in the process as Alanna is going to be.
Granted, there probably won't be TOO too much in either piggy bank (although, Alanna is very resourceful when it comes to "finding" change.... as is Lydia... they start young) kids are excited about the prospect of having their OWN money. Being able to buy something that THEY earned the right to buy. They don't like asking for something and being told NO. I know... surprise right? They like knowing that they contributed to the trip in some way. They like knowing that this trip was made possible, in part, by what they put in their piggy banks.
I'm going to have to make my own Disney piggy bank here soon and start shuffling change from the couch cushions into the cavernous hole that needs to be filled in 3 years.
If you want to go to Disney, but can't do it right now... don't worry about it. Give the kids something to work towards. Something to look forward to. Stop feeling bad having to tell them "Not this year" or "I'm sorry, it will have to wait". Tell them "Yes... we can go to Disney". Tell them when. And tell them what they have to do in the mean time.