Can someone help me on my 98 Toyota Camry's Relay Fuse problem?

[fonsiboy]

Ok, I just picked up a 98 Toyota Camry Xle, the Fully Loaded V6 one. It runs perfect but has a problem. Im 17 years old and there is only so much I know about cars but not this. When I turn off the car, or take the key out, there is a little rattling noise thats coming from the relay fuse box. When I put the key back in as if Im going to turn it on, it stops. So its only when I take out the key. Can someone please help me, whats wrong, how much is it, is it really expensive and where is the best place to take it to. Please help me! thanks! Greatly appreciate it