S.L.
you're smart to look start now. I'm trying to find a minnie mouse for my daughter (turning 5) in october!! Here's a few sites I found helpful:
http://members.tripod.com/Parties_by_Stacey/photos.html
I also found some on these...but you should probably ask for a picture because not all of the them post up the pic.
http://www.partypop.com/search.cfm?kwd=minnie+mouse&l...
Good luck and if you happen to run into a Minnie Mouse that looks like the real deal please let me know.
S.