Sometimes I pay the kids to find a lost item for me, generally for something important like my keys or a cell phone with a dead battery.  Whoever finds it gets $1.

Here is a conversation from earlier today with my 5 year old.

Elizabeth:  Can I find your keys and get a dollar?
Me:  Um, no thanks, I know right where they are.
Elizabeth:  But I don't.

She stared at me for minute, like I was the crazy one, like it is some sort of game we play when kids are bored.  Apparently I've been good at hiding my panic/frustration....because I really don't offer this kind of cash except when I'm a bit desperate.

Thankfully no one has used that as a real opportunity and relocated the items themselves :)