@wdwpracticalprincess - you are right - offsite rentals *are* typically cheaper - for
ECVs.
I assume that she is not comfortable using an
ECV? An ECV can be an excellent option if she is able to safely drive one. Even if she can't drive it up the bus ramp herself (and a family member has to do it for her, the bus drivers can not) an ECV might be something to consider; you have time for her to get used to the idea, and practice with the ones available at most grocery stores, Wal-Marts, Targets, etc. If she can master one of those big beasties, a little rental
scooter will be very easy for her to use!
But if, for whatever reason, an ECV is not an option, please remember - if you all (as a family) decide to go to Downtown Disney/Disney Springs, or maybe over to Boardwalk to shop and look around, or maybe Hoop-Dee-Doo... you will be glad you have the chair for her! Not everything at WDW that requires a lot of walking is "park specific".
Even at some of the larger resorts, it may be helpful just to go back and forth to the food court; depending on where your rooms are, it can be quite a hike to meals and bus stops!
So, when you look at your trip as a whole - not just "park days" for her - see if it is possible that the wheelchair will be helpful during other activities and events. That may help put the overall cost into perspective.
Also - you may want to consider renting locally (before you leave home) and bring the chair with you. Not only is it possibly cheaper - but especially if you are flying - there can be LOTS of walking at airports; it may be helpful there as well.
Would a rollator be a better choice for her? Rollators are like walkers that have a seat; most can be folded for easy transport, and some can function as a "travel chair" where someone else pushes the seated individual. Something like
this.
Either way, be sure to bring bike gloves for the "pusher" to wear. I can tell you from personal experience that it does not take long before your hands will be sore, and even blistered from pushing the chair. The bike gloves make a *huge* difference.
Last thing to consider - some churches, civic groups, etc. have wheelchairs that you can borrow for short periods of time, rather than rent. For example, our local Masonic Lodge has a couple of wheelchairs and several pairs crutches in different sizes, and I think a walker they loan out to local residents for short periods. Our church also has similar equipment to loan as well; might be an avenue to explore. Just make sure that the borrowed equipment is in safe, clean, working condition prior to leaving on your trip.
Wishing you and your family all the Magic you can find on your trip!