I too am a pre-buyer of souvenirs.
I started doing it about 3 years. The
Disney store had some really cute things on sale about a month before we went. I got t-shirts, PJ's and socks plus note pads and pencils. Since then I have done it 3 times and have already started for this years trip in June.
I just bought t-shirts at the Disney store for $7 each and in January I bought a ton of stuff at Dollarama.
My kids are older (18 and 9) they bring their own spending money on vacation but they get a kick out of getting the stuff that I give them. Some of it they know about in advance and some of it is a surprise.
I really like the idea from 'Disney Ontario' about the bags....I'll steal that one if know one minds.