Best solar chargers on a budget? Plus other electronics questions.

I actually have a few different targets I'm aiming at here.

1. We have a friend who has a son who graduated high school this year. He sails competitively and as a graduation gift we're thinking of getting him a small solar charger. There are a few stipulations on that one. First, it needs to be waterproof. Second, apparently if they exceed 100Wh you can't take them on a plane, so we need something south of that. Finally, can such things be had at $50 or less that are any good?
2. I'll be going camping later this summer and I'd like to get something for myself to keep the phone charged, but it doesn't have to be waterproof. I'd be willing to spend a little more to maybe get some more features but I just don't know where the sweet spots are between price, features and quality with solar chargers, and so I don't know what a realistic price range is. What do you think?
   1. But as a sub question, should I just get a small Jackery or other brand power station if I just want to be able to charge my phone a few times?
   2. And if I do get a power station, how big of an inverter would I need to recharge it?
3. What about portable electric coolers - best bang for the buck?

I'd love your experienced input. Thanks.