App Idea?

You can't fit an iPad in your pocket right? So sooner or later there's going to be a number of careless people who leave their iPad behind, and ultimately lose it. So my idea for the app is to use bluetooth to make a connection between your iphone or ipod touch and your ipad, so whenever you walk far enough away from your ipad your iphone will sound an alarm or something. Now this would be hard to implement until multitasking is available and it can be run simultaneously.
So my question is how much would you pay for this if you pay at all?

 

I also thought that I could make it tell you the location of either iphone or ipad over 3G