I don't remember the exact cost of everything we purchased last year, but following is a run-down of the things we bought w/ the estimated costs:
Small Stuffed Minnie Mouse for DD (~ $15)
Small Stuffed Mickey Mouse for DS (~ $15)
4 "Happiest Celebration on Earth" T-Shirts (~$15-$20/each)
Buzz Lightyear Spinner (~$10)
Cinderella Spinner (~$10)
Fort Wilderness Christmas Tree Ornament (~$8)
3 "Happiest Celebration on Earth" Christmas Tree Ornaments (~$15-$20/each - one for me, one for my mom, & one for my MIL)
"Wishes" CD (~$15)
2 "Happiest Celebration on Earth" Photo Albums ($20-$25/each)
2 Coffee Mugs (~$10/each)
2 wooden WDW picture frames (~$10-$15/each)
1 castle picture frame (~$20)
1 Minnie Mouse china figurine for DD (~$8-$10)
1 Mickey Mouse china figurine for DS (~$8-$10)
1 pair of silver Tinkerbell earrrings for me (~$20)
1 Mickey Mouse watch for DH (~$50-$75)
Coffee for my parents who got our mail & fed our cat while we were gone(~$10)
Pooh Stickers for my niece (~$5)
3 Pressed Pennies ($1.50)
So, I guess maybe between $375 & $475... $500?
Additionally, both my parents & my DH's parents gave DD & DS their own "spending money". And, in the months preceding our trip, we gave them the opportunity to earn Disney Dollars by doing things around the house like picking up their toys. So, I think they each had about $50-$75 of their own spending money. We made them to wait until our last day to spend it when we went to DTD. (They kept seeing things in the parks they wanted, & we kept telling them to wait until we go to DTD & then they could buy whatever they wanted after they had a chance to see everything.) DD bought a stuffed Lady & a stuffed Tramp and a Little Mermaid playset. DS bought an "American" Buzz Lightyear (in his patriotic outfit), a stuffed Dumbo, & a Peter Pan playset.