I don't really recall a great deal of movies at disneyland, but I could be wrong. We have had to get all of our "hard to find" ones through the Disney Movie Club - and then DH has actually purchased a couple of "vaulted" movies off ebay because he "had to have them".
Yes I have had some luck finding rare movies, not sold in the stores. But of course I have to agree with the above comment, about the vault. I have always wanted Song of the South. I thought they were supposed to release that this year. I signed a patition for it. What the heck Disney?
If you are local, the Disney Soda Fountain & Studio Store in Hollywood allows you to search their Buena Vista kiosk for DVD's. I'm not sure if you can purchase ones that are "back in the vault."