FYI: The $25 box is checked automatically and there is no confirm window after the paypal window. I just accidentally payed $10 over what I wanted to pay. That "checkout area" needs to be a little more clear I think. I didn't even realize that was the checkout area. I honestly didn't even notice the amount bubbles and was wondering when I was supposed to plug in what I wanted to pay. I was super confused when I got to the last page. Didn't notice until I got the paypal notification on my phone and went back to the main page.
I realize I'm dumb, but maybe someone will read this and not make the same mistake.
Note also if for some reason the payment fails (for example an error with the captcha) the payment resets to $25. Didn't catch it the second time through the payment process.
Yep, I also did the same and accidentally clicked on the "Pay Instantly with Paypal" button -- which indeed did what it said it would. I supposed I'm not too torn up about it since I put a large majority of the purchase towards charity, but I feel like I fell for a subtle UX trap even after 10+ Humble Bundle purchases.
I realize I'm dumb, but maybe someone will read this and not make the same mistake.