ECV and Wheelchair Rental at Disneyland:
Several people, here and on other boards, have recommended:
Deckert Surgical Supply in Santa Ana at (714) 542-5607 (I have never found a website).
Orange County Medical Supply at (714) 956-4690
Both will deliver to your resort.
actually Disneyland ECV's are $55 a day; you put up $75 at the beginning of the day and they refund to you $20 when you return the ECV.
You also can't take the Disney ECV out of the parks or Esplanade--this means if you are staying on-site or at a hotel near the park, and would otherwise walk to the park from the hotel, you will need to walk to the rental area in the Esplanade. If you rent from one of the off-site companies you can easily ride the ECV from your hotel (most helpful at the end of the day!)
I have used both Deckert's and OC Medical--lately OC Medical more. $45 a day may not seem like much of a discount but it's the going rate here in Calif. I think there's more competition in Florida and prices are less.