Thanks Elise. It's actually something we're thinking about for my mum. I know in the long run it's probably better to rent from an outside vendor but she a bit concerned about getting it on and of the buses as she doesn't use one normally we just think that for a 10 day park trip she maybe better off with one.
If your mum isn't comfortable getting on the buses one you can drive it on for her - I have seen that plenty of times. The bus drivers are also good at giving directions to help get you in the right place.
The bus drivers are amazing with ecv's, a few times they let dh take a seat on the bus and steered it on themselves. Only on one occasion did we have to wait for another bus as there were already 2 ecv's in the line ahead of us. I think we rented from Apple or Buena Vista, they deliver them to the hotel and collect them on your departure day, you have a number to call if anything goes wrong. I think it was just under $300 for two weeks. We love that most of the ride lines let you join with the ecv, a few have you use the fast pass entrance and an odd one or two take you through separately, but mostly you stay in the normal queue. We did Universal 3 years ago and they weren't very ecv friendly.