I found my 22" OTS in the trash at my old apartment complex. The legs weren't put on correctly and it caused the wheels to fall off. I went to a local true value, bought a new hinged cooking grate (was not going to cook directly on something pulled out of a dumpster) and a cover. I asked them "do you know know where I can find just the wheel caps?" and the guy just gave me a couple of them, no charge.
One complete grill for next to nothing.
The thing that really gets me about this, it was an '08 grill! Barely used! Who would dumpster that? Well, they did use the ash catcher INSIDE the kettle, which melted it (and Weber send me a new one for free).
Anyways, enough rambling, if you find a nice guy at your local true value, you might get Weber OEM caps for free.
I hope the kid likes the grill! Be sure to teach him to use a chimney starter from the get-go!