You might want to consider picking up two. As fragile as they are, it is good to have a spare on hand just in case. And one of Murphy's corollaries is that if you have more than you need, you'll never need the spares. ;D
Yay, I get to be an exception again! I had my first hydrometer for about 5 years, then a friend gave me his old brewing stuff which included two or three hydrometers, and then a friend being "helpful" in my kitchen (after I told her not to) managed to break my original one and crack my test tube... Yay for spares!