For candling, you need high lumens (that's the brightness measure). Most flashlights you find, especially small ones, don't have very high lumens.
We spent 30 bucks on the 220 lumen small flashlight I use to candle. DH has this flashlight thing going on. They draw him like a magnet. He picked up one of these for in his truck. When I couldn't see into my eggs with the other flashlight I was using, I borrowed it and it worked well enough that he bought me one just for that.
Only problem is, the lumens aren't high enough for me to see into a lot of my EEs eggs. If they lay the very thick shells, or have the olive shells, I can't see. I'm jonesing for the 800 lumen light I saw at the sporting good store. Bringing myself to pay how much they want for that isn't working right now.