I personally find that the $150 minimum the website above requires is more than I want to spend.
Here's a couple of suggestions. If you go to the Animal Kingdom, you could plant a special surprise in the Dinosaur Dig while he's not looking and let him dig it up. You could also laminate a card stating "His name is ___" and hold it up behind his back - that way the characters that talk can greet him by name and he'll know he's really special since the characters know him by name (just be sure to make the sign large enough they can read easily). My son is a big Star Wars fan, so I purchased the Star Wars books I found in the children's section of the bookstore and surprised him with a couple during our trip. You may want to utilize some of the ideas posted below too.
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I originally posted this under a second id last week due to password problems. You can substitute the breakfast at the Castle to breakfast with one of his favorite characters.
I took my 8 yr old niece to WDW and wanted to make it really special because it was her first vacation ever. Before we left, I wrote notes for each night we were there signed by different characters and bought little surprises to leave with the notes at the foot of the bed. After that first morning, her first reaction to waking up was looking immediately at the end of the bed to see who had visited the night before and what they left her.
I bought some trinkets at the
Disney Store prior to leaving on our trip, as well as looking at Target, Wal-Mart, etc. They ranged from Disney character cookies, a straw w/Minnie on the top, some new T-shirts, the large striped sucker Disney sells (found at Target for $1.50 instead of the $3-$4 at park). I planned the trip out so the notes and surprises were related to whatever park we were visiting that day and who we were likely to see. The morning of our breakfast w/Cinderella, I left a T-shirt dress I'd found on sale at the Disney store for $15 and the note read somthing like, "To a special princess, we're looking forward to meeting you this morning! Love, All the Disney Princesses". When we arrived at the castle, the lady at the door told her, "Oh, we've been waiting for you. You have the special table." Once inside all the Disney princesses worked their way around the room and each of them called her princess. I could not have planned it better if I'd paid everyone to do it. My niece's eyes were so shiny they absolutely sparkled. It's been two years and my niece still talks about her trip.
Oh, I almost forgot... I discovered the clerk at the Disney store was going two months before we did and I gave her some money to bring me back an autograph book. I found pictures on the internet of as many Disney characters as I could find that I thought would be at the park. I copied and pasted them into Word and then printed them off, cut them out and pasted them (one on each sheet, using a stick glue) in the autograph book. As she came across different characters in the parks, she found their picture in the book and had them sign on that page. Everyone made a big deal out of having their picture in the book. I took pre-cut clear contact paper in the backpack and after the character signed it, I would put the clear contact paper over that page so the signature wouldn't get smeared. I also placed the autograph book into
a baggie so it wouldn't get wet on the water rides. I did one for my 12 yr old son too and we're planning on taking it back to WDW to see how many more signatures we can get.
I also bought her a Disney journal (found at Target) and had her write her favorite ride, show, food, character meeting, etc. about that day. I had her skip a couple of pages in between the days and when we got home, I placed her pictures with the characters on the pages for that day.