smart key issues

So I'm down to one smart key and it doesn't work anymore. Anyone know of any legit sites that might sell new smart keys? I called the dealership to see what ridiculous price they charged and yes, it's ridiculous. Out the for for the smart key, emergency key and programming of both is $480 out...

I have two concerns and welcome suggestions from expert. First I am having two card type Mitsubishi smart card keys and one is having starnge problem. Its locking and unlockin but after engine start Key Light blinks with beep sound. It is indication that sensor couldn't locate key inside car...