Amazon has portable solar LED light bulbs [amazon.com]
on sale when you apply coupon code P6YNFD32
The single bulb is $6.37. The two-pack is $11. The three-pack is $15.65.
The bulbs have solar panels right on them, and a hook to hang them. They're great for camping! The one we have gets way brighter than I expected it to.
They're on sale through the end of the month.