Not fair to turn this into a DQG flame thread. But, I love their Spy and have zero problems with them. I hear problems on the other lights. So I stay away.
Budget for this project??
Bare in mind, "small" is relative to the beholder of small. Don't believe me, you could have asked Biggie Smalls. What a conundrum!
A "small", but not the worlds smallest, is the cigar shape lights. One of the best values right now is at Banggood. search BLF A6. This light is, IMHO, a freaking killer deal. Don't let the price fool you. It blows away lights 10xs is price.
Check that out and see if the size is too big for you.