Wyldflower--We jsut got back from our 4th trip in 3years! I definitely recommend the mousesavers website for tickets vendors. On my last trip in Feb we used ticketmania & they delivered the tickets to our hotel for us-You can pay for tickets over the phone or internet, but must give them at least 3 business days! (also we always stay on site, so not sure if you can get them delivered, but they will also mail them, or you can pickthem up down there-this does 2 things-saves some money from WDW's prices & like previous poster said, you don't have to start your trip standing in a WDW line--There will plenty of those!! ha!
As for the $20, it won't go far in the parks, but they now have a new store in DTD that has all things for $10 or less, so it does allow them to look at items & know they are in their price range. Also, previous poster had good ideas about outlet mall-just be warned we went there on a rainy Sunday & it took us 1 hour to go 1 mile to get into the outlet b/c of the lights & horrid traffic! (go on a weekday!) You also could tell them to take their first few days in WDW to decide what they want since the $20 will only buy 1 or maybe 2 things & then after looking for most of the week, they won't impulse buy-they will know what still sticks in their mind as their favorite thing. I would recommend DTD for shopping-it has great atmosphere & alot of shops all in one place. ALso there is a list of free things to do at WDW, & it really is a great resource-pm me & I can give you the site-I think it was mousesavers as well, but will have to research it.
Also, here's a thought buy two autograph books before you go (if you think they would get a kick out of getting autographs--I know my kids did when they were 8 & 5 & my niece is 9 & loved it in Feb.) at a Dollar store or place like that & marker. You don't want to have to buy disney autograph books! It will just eat the money up.
I don't have any experience w/ Pal Mickey except that I have heard he is very hard to hear b/c of all the noise in the parks. Just a comment I read on one of the disboards. If you have any other questions-I love Disney as do all people here on the boards & love helping people to have the best experience ever! Debbie (Sorry for the long post--I just couldn't help myself! You can certainly pm or e-mail me for more ideas!)