You can make one with a bulb/LED and a paper clip...
Use the bulb from the flashlight or a LED.
- set the battery on the positive end of the battery to be tested.
- take a paper clip and bend it into a makeshift "C"
- touch one end of the paper clip to the negative (flat/bottom) end of the battery.
- touch the other end of the paper clip to the bulb side.
You may need to use adhesive tape to help you, or get a friend / third hand to help hold the items together to make a good contact.
If the battery is good, the bulb will light up (if correct connections are made on the battery AND bulb).
The brighter the bulb, the more juice the battery has.
NOTE: If the bulb doesn't light up right away, make sure you fiddle with the connections a bit before you discard the battery.