For ~40$ range I suggest Jetbeam BA/BC series. For less, take a look at Olight "i" series or ITP "Eos" series. Avoid cheap ***Fire lights, because their reliability is not so good and sometime they need additional soldering job to fix factory negligence.
You can't go wrong with the new solarforce L2. Best light for the money. I'm really impress with their quality. Well it is a only budget light i trust to put on my AR.
Are you talking about lights with standard batteries, or also LiIon batteries? I only give away lights that run on standard cells. (AA/AAA) Otherwise you have to factor in batteries/charger/voltmeter etc. and a small powerpoint presentation on how to charge 18650 batteries safely. ;-)
If parents / friends are more technically oriented, you could get those lights using Li-Ion batteries (14500, 16340, 18650).
On AA / AAA -format you basically need just the light. Batteries are available everywhere.
If you want to use Li-Ion, you need to buy good batteries AND proper charger also.
This adds up at least 15$ but more likely 30$.
If you can decide the battery configuration (means a lot to the size of flashlight), it would be easier to recommend "the safest first tries" what to buy.