They are really strict about the lockers, but the lockers are all really close to ride entrance/exits, and free for the time it takes to ride the ride. We were there for 9 days in November, rode everything a zillion times, used lockers every day and didn't pay one cent. It's really not that much of a hassle.
On the other hand, I also have a running belt thing that is just a stretchy tube with a couple slits to slide things into. It's the perfect size for a small wallet or cellphone. And that's exactly what I kept in there on the couple days I wore it in. I did remove my phone for the rides, but usually kept my wallet and room key. It was under my shirt, flush to my skin and not going anywhere unless they pulled it over my head. No one saw it or said anything. So if you have something that you don't trust in the lockers, you have options, but honestly I recommend against it. It's uncomfortable to wear all day and really just unnecessary.