One that might fit most of your criteria is an Energizer Folding LED Lantern.
Energizer LED Folding Lantern

These were discontinued about a year ago, but are back in production now. I've seen them for sale in Target stores. About $8, run on 4AA batteries, has 2 light output levels, runs for about 100 hours on high, 200 on low (approximate). They're compact and a good value...light output is small, though - definitely sufficient for inside a tent, OK for say a picnic table top in a campground, but not going to light up a whole room so everyone can read, but sufficient to light a room so you can find your way around.
They're small and easy to fit in a jacket pocket, and cheap enough you wouldn't feel bad about losing/breaking one. Definitely not waterproof, though, if that's a hard and fast requirement.

Here's a review:
Review

Dave