Have you checked your local FreeCycle group? Someone may have one they'll let you 'borrow" just don't actually ASK to borrow it because that's against FreeCycle policy.
What I did was ask if anyone had one they no longer need for the weeks I was going. I had a lady e-mail asking if I'd like to borrow hers. Good deal!
But...now the flip side. We took it to the MK with us, where it was used for a few hours then put up. My 6yo daughter wanted to carry it and got tired of listening to it tell the same jokes, it got heavy, even put on a <think they are called Lanyards> to make it easier to carry, so into the stroller he went.
They are VERY hard to hear in the park and having to hold it to your ear to hear quickly lost it's appeal.
If you really must have one, check your local FreeCycle list, or try Craigslist if you live in a bigger city. And you can always buy one then sell it on ebay when you are done.