Well, since your food is being paid for, I'd say yes if you can control your shopping.
Souveniers range in price from a few dollars to thousands of dollars.
When I go, I'm not into "big" souveniers. I collect antenna toppers for my car which cost about $4 each. I like to get functional things also, like pens, coffee cups etc.
We don't really budget for souveniers. If we are in a store and we want something and really feel like it's something we must have, we buy it. Obviously, we are not doing this with $100 items. But the odd pen here and there or photo frame etc.
I'd just set aside some cash for souveniers, rather doing a per day thing. And try to wait until later in your trip to go shopping. That way, you'll have a chance to look around a little and decide what you want.
Remember, you can always order anything from the shops in the parks via WDW mail order when you get home.