I currently work with Middle School students. I do expect a fair number of drops, bumps, and spills. It's photography business for the 7th grade today. A kit was was dropped and the bayonet on the lens was busted all the way around. Upon inspection of the body itself, it seems to work just fine. I can't quite inspect the entire function of the lens, but from the aperture I can see no visible damage to the glass or mechanisms. I can buy a used lens Canon EFS 18-55mm for less than $55 or fix the bayonet for $20 and risk something else being wrong with it as a result of the drop.
None of the reputable dealers in my area will sell me a bayonet. If it was my own money, I would buy a bayonet and gamble that nothing else was wrong with the lens and that the bayonet was a quality part. But, I don't have to play this game. I'm going to replace the lens with a used one and hang on to this one until the next accident. We'll find out then if the lens is still good. Unless a kid shatters the bayonet again (sad trombone).