What's inexpensive? If you need something that's kid proof and rock solid reliable, I'd say Fenix E05. At $20 or so it might be out of your price range but you should realize go really cheap and you may have lights that will require some initial work to make reliable.
If you're a pretty handy individual willing to take apart, clean, tune up and reassemble a flashlight then I'd say get a Uniquefire G10 from dealextreme. It's about the least expensive Cree XP-G flashlight available at about $14 with shipping. It's so far my favorite compact light. On 1 AA nimh it is darn bright and has a very smooth high quality beam to it. An running off a 14500 li-ion it's as bright as any other XP-G light out there, which is to say very very bright, for comparison it's almost as bright as my Aurora AK P7 led light yet fits in the palm of my hand.