Before 9/11 the lockers (which are always located near the entrance of each park) were a great deal (about $1) and we always used them for the convenience. But after 9/11 I think they wanted to discourage people from using them and the price went up astronomically. (I think to about $7) I believe you can transfer the use from one park to the other in one day, but we have stopped using them. Just too expensive for the convenience.
Now we bring in disposable ponchos from
Walmart (the camping section has them) that can be slipped in a pocket and used if needed. We carry Brita water bottles when it is hot, a small camera, and I take a small change purse with my license, credit card, room key, $, lipstick, and that's it. Without kids, or with older ones, this strategy gets us through the parks.
If you think you're going to need emergency changes of clothes, and you would normally drive to the parks, you could always leave all emergency items in the trunk, especially if you arrive early and park close to the entrance. Except at the MK, and during the busiest seasons, the lots aren't that bad. But if you don't drive, renting a locker might be your best bet, since it would cost you the same to park your car as it would to rent a locker.
Hope this helps.
