You didn't mention if the souveniers are for yourself or others.
If I'm buying for others--and frequently myself--I try to purchase items that are specifically have the WDW logo on them--or something of the sort--and are reasonably useful.
Rulers. Can't remember how much they are, but they are great gifts for children, teachers, office colleagues--anyone who can use a ruler and would enjoy having a touch of Disney around them. Bought one for myself, too!
Walt Disney World tote bag. It was one of the least expensive bags and the one I liked best! *LOL* It's navy blue with the WDW logo on it. It's great as a carry-on bag, casual briefcase, or just for general use. I wanted one with a secure top closure--a zipper, in this case. I think it was around $30.
Trading pins. Around $6 and up. I purchased a few that were WDW specific that non-Disney people would recognize. I have a few obtained through special promotions (
MVMCP,
MNSSHP, "gift" as part of a WDW package, and a few purchased for specific resorts.
Waterproof card/cash holder. Available at all of the resorts. Don't recall seeing them in the parks, although they could be there. Great for anyone who goes to the beach, lake, public pool, water parks, etc.
I don't purchase a lot of souveniers for myself (tote bag and ruler excepted *LOL*), but when I do it's usually a barette, jewelry, artwork--something I can enjoy and use on a regular basis.