I would seriously consider using ebay. I have bought lots of wonderful items on ebay. If you want to PM me, I will tell you the name of my favorite seller whose items are very reasonably priced -- I have bought my kids pins, pin lanyards, beach towels, the light up items they sell at the parades, etc. By buying them ahead of time, I was able to budget better and the kids didn't ask for all sorts of stuff in the parks -- they got to bring their light up princess and buzz lightyear things with them.
I have also found LOTS of Disney merchandise at the dollar store, including stickers, coloring books,etc. and I bought light up necklaces there to take with me and give to the kids in the parks, when they asked me to buy them.
It's so much fun!